Artykuły w czasopismach: „Magneto-electric Coupling - Single Crystals”

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Hu, Chengpeng, Xiangda Meng, Mao-Hua Zhang, Hao Tian, John E. Daniels, Peng Tan, Fei Huang i in. "Ultra-large electric field–induced strain in potassium sodium niobate crystals". Science Advances 6, nr 13 (marzec 2020): eaay5979. http://dx.doi.org/10.1126/sciadv.aay5979.

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Electromechanical coupling in piezoelectric materials allows direct conversion of electrical energy into mechanical energy and vice versa. Here, we demonstrate lead-free (KxNa1−x)NbO3 single crystals with an ultrahigh large-signal piezoelectric coefficient d33* of 9000 pm V−1, which is superior to the highest value reported in state-of-the-art lead-based single crystals (~2500 pm V−1). The enhanced electromechanical properties in our crystals are realized by an engineered compositional gradient in the as-grown crystal, allowing notable reversible non-180° domain wall motion. Moreover, our crystals exhibit temperature-insensitive strain performance within the temperature range of 25°C to 125°C. The enhanced temperature stability of the response also allows the materials to be used in a wider range of applications that exceed the temperature limits of current lead-based piezoelectric crystals.

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Takeda, Hiroaki, Satoshi Tanaka, Hiroyuki Shimizu, Takashi Nishida i Tadashi Shiosaki. "Growth and Electric Properties of Al-Substituted Langasite-Type La₃Ta_0.5Ga_5.5O₁₄ Crystals at High Temperature". Key Engineering Materials 320 (wrzesień 2006): 239–42. http://dx.doi.org/10.4028/www.scientific.net/kem.320.239.

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We report an effective substitution of aluminum for gallium in langasite-type La3Ta0.5Ga5.5O14 (LTG) crystals for use in a pressure sensor at high temperature. Al-substituted LTG (La3Ta0.5Ga5.5-xAlxO14; LTGAx) single crystals up to the solubility limit of x=0.5 have been grown by the conventional Czochralski technique. The electric properties of the LTGAx crystals were investigated and compared with those of LTG. By Al substitution, the piezoelectric constant d11 and the electromechanical coupling factors (k12) became slightly larger. The LTGAx crystals showed a lower temperature dependence of d11 and a higher electric resistivity ρ than those of the LTG crystals.

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Niklasch, D., J. Dadda, H. J. Maier i I. Karaman. "Magneto-microstructural coupling during stress-induced phase transformation in Co49Ni21Ga30 ferromagnetic shape memory alloy single crystals". Journal of Materials Science 43, nr 21 (listopad 2008): 6890–901. http://dx.doi.org/10.1007/s10853-008-2997-z.

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Mehner, Erik, Juliane Hanzig, Sven Jachalke, Florian Hanzig, Matthias Zschornak, Hartmut Stöcker i Dirk Meyer. "Electric field induced pyroelectricity in strontium titanate". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C44. http://dx.doi.org/10.1107/s2053273314099550.

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Pyroelectric materials have a broad spectrum for practical application. Apart from the established infrared sensor technology, recently the pyroelectric effect has been employed unconventionally in waste heat recovery, X-ray generation or water disinfection. This coupling phenomenon is the temperature dependence of a ferroelectric's spontaneous polarisation. A crystal structure that allows pyroelectricity cannot have an inversion centre, if it had a polar axis would not exist. Hence the well-known perovskite strontium titanate, crystallizing in the space group Pm-3m, is known to be dielectric. Nonetheless, under an external electric field of 1MV/m charged defects like oxygen vacancies redistribute in a strontium titanate single crystal, leading to a distortion of the unit cell and subsequently to the formation of a defect structure called the migration-induced field-stabilized polar (MFP) phase [1]. Raman scattering shows that the MFP phase of strontium titanate may exhibit broken centrosymmetry, suggesting the existence of a polar axis. Here, we investigate the pyroelectric properties of strontium titanate single crystals at room temperature during these electroformation cycles with a modified Sharp-Garn method [2]. Our frequency and field dependent measurements indicate the pyroelectricity of the MFP phase. Additionally the measurement method elucidates the kinetics of the oxygen vacancy migration as well as electric properties during electroformation. Inducing pyroelectricity in a centro-symmetric crystal structure opens the scope for a new class of pyroelectric materials.

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Rout, Jyoshna, i R. N. P. Choudhary. "Study of multiferroic properties of Bi2Fe2WO9 ceramic for device application". Journal of Advanced Dielectrics 06, nr 03 (wrzesień 2016): 1650023. http://dx.doi.org/10.1142/s2010135x16500235.

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The Bi2Fe2WO9 ceramic was prepared using a standard solid-state reaction technique. Preliminary analysis of X-ray diffraction pattern revealed the formation of single-phase compound with orthorhombic crystal symmetry. The surface morphology of the material captured using scanning electron microscope (SEM) exhibits formation of a densely packed microstructure. Comprehensive study of dielectric properties showed two anomalies at 200[Formula: see text]C and 450[Formula: see text]C: first one may be related to magnetic whereas second one may be related to ferroelectric phase transition. The field dependent magnetic study of the material shows the existence of small remnant magnetization ([Formula: see text]) of 0.052[Formula: see text]em[Formula: see text]/g at room temperature. The existence of magneto-electric (ME) coupling coefficient along with above properties confirms multi-ferroic characteristics of the compound. Selected range temperature and frequency dependent electrical parameters (impedance, modulus, conductivity) of the compound shows that electric properties are correlated to its microstructure. Detailed studies of frequency dependence of ac conductivity suggest that the material obeys Jonscher’s universal power law.

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Amin, A. "Electromechanical properties of high coupling single crystals under large electric drive and uniaxial compression". IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 52, nr 10 (październik 2005): 1632–37. http://dx.doi.org/10.1109/tuffc.2005.1561618.

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Chen, Feifei, Xiufeng Cheng, Fapeng Yu, Chunlei Wang i Xian Zhao. "Bismuth-Based Oxyborate Piezoelectric Crystals: Growth and Electro-Elastic Properties". Crystals 9, nr 1 (6.01.2019): 29. http://dx.doi.org/10.3390/cryst9010029.

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The non-centrosymmetric bismuth-based oxyborate crystals have been extensively studied for non-linear optical, opto-electric and piezoelectric applications. In this work, single crystal growth and electro-elastic properties of α-BiB3O6 (α-BIBO) and Bi2ZnB2O7 (BZBO) crystals are reported. Centimeter-sized α-BIBO and BZBO crystals were grown by using the Kyropoulos method. High resolution X-ray diffraction tests were performed to assess the crystal quality. The full-width at half-maximum values (FWHM) of the rocking curves were evaluated to be 35.35 arcsec and 47.85 arcsec for α-BIBO and BZBO samples, respectively. Moreover, the electro-elastic properties of α-BIBO and BZBO crystals are discussed and summarized, based on which the radial extensional and the face shear vibration modes were studied for potential acoustic device applications. The radial extensional mode electro-mechanical coupling factors kp were evaluated and found to be 32.0% and 5.5% for α-BIBO and BZBO crystals, respectively. The optimal crystal cuts with face shear mode were designed and found to be (YZt)/−53° (or (YZt)/37° cut) for α-BIBO crystal, and (ZXt)/±45° cut for BZBO crystal, with the largest effective piezoelectric coefficients being in the order of 14.8 pC/N and 8.9 pC/N, respectively.

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Xu, Chengchao, Jun Li, Huanfang Tian, Zi-An Li, Huaixin Yang i Jianqi Li. "Flux Method Growth and Structure and Properties Characterization of Rare-Earth Iron Oxides Lu1−xScxFeO3 Single Crystals". Crystals 12, nr 6 (26.05.2022): 769. http://dx.doi.org/10.3390/cryst12060769.

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Perovskite rare-earth ferrites (REFeO3) have attracted great attention for their high ferroelectric and magnetic transition temperatures, strong magnetoelectric coupling, and electric polarization. We report on the flux method growth of rare-earth iron oxide Lu1−xScxFeO3 single crystals through a K2CO3-B2O3-Bi2O3 mixture as a flux solution, and give a detailed characterization of the microstructure, magnetism, and ferroelectric properties. X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) measurements revealed that the obtained single crystals can be designated to three different crystal structures of different chemical compositions, that is, Lu0.96Sc0.04FeO3 (perovskite phase), Lu0.67Sc0.33FeO3 (hexagonal phase), and Lu0.2Sc0.8FeO3 (bixbyite phase), respectively. Magnetic measurements indicate that the perovskite Lu0.96Sc0.04FeO3 is an anisotropic hard ferromagnetic material with a high Curie transition temperature, the bixbyite Lu0.2Sc0.8FeO3 is a low temperature soft ferromagnetic material, and the hexagonal Lu0.67Sc0.33FeO3 exhibits multiferroic properties. Lu0.67Sc0.33FeO3 possesses a weak ferromagnetic transition at about 162 K. We further investigate the ferroelectric domain structures in hexagonal sample by scanning electron microscope and the characteristic atomic structures in ferroelectric domain walls by atomically resolved scanning transmission electron microscope. Our successful growth of perovskite Lu1−xScxFeO3 single crystals with distinct crystal structures and stochiometric Lu-Sc substitutions is anticipated to provide a useful ferrites system for furthering exploitation of their multiferroic properties and functionalities.

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Yin, L. H., J. Yang, P. Tong, W. H. Song, J. M. Dai, X. B. Zhu i Y. P. Sun. "Spin glass and magnetoelectric effect in BiFeO₃-Bi_0.5K_0.5TiO₃-Bi_0.5Na_0.5TiO₃ single crystals". Journal of Applied Physics 132, nr 4 (28.07.2022): 044101. http://dx.doi.org/10.1063/5.0092058.

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We report a cluster spin glass behavior, multiferroicity and magnetoelectric (ME) effects in the single crystals of 0.46[Formula: see text]-0.54[Formula: see text]. The crystals are found to possess a pseudo-cubic structure with a weak tetragonal distortion and show ferroelectricity at room temperature with a ferroelectric curie temperature of [Formula: see text] K. The cluster spin glass state in the crystal is evidenced by detailed dc and ac magnetic experiments, including thermo-remnant magnetization, aging effect, memory effect, etc. Magnetodielectric effects, poling enhanced magnetism, and electric field induced acceleration of magnetization relaxation in the spin glass state are observed and ascribed mainly to spin-lattice coupling. These results might suggest an effective route to improve ferromagnetism and ME effects by constructing a spin glass state in [Formula: see text]-based antiferromagnetic multiferroics.

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Chen, Mingce, Qi Shao, Wenda He, Dong Wei, Chai Hu, Jiashuo Shi, Kewei Liu, Haiwei Wang, Changsheng Xie i Xinyu Zhang. "Electrically Controlled Liquid Crystal Microlens Array Based on Single-Crystal Graphene Coupling Alignment for Plenoptic Imaging". Micromachines 11, nr 12 (26.11.2020): 1039. http://dx.doi.org/10.3390/mi11121039.

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As a unique electric-optics material, liquid crystals (LCs) have been used in various light-control applications. In LC-based light-control devices, the structural alignment of LC molecules is of great significance. Generally, additional alignment layers are required for LC lens and microlens, such as rubbed polyimide (PI) layers or photoalignment layers. In this paper, an electrically controlled liquid crystal microlens array (EC-LCMLA) based on single-crystal graphene (SCG) coupling alignment is proposed. A monolayer SCG with high conductivity and initial anchoring of LC molecules was used as a functional electrode, thus no additional alignment layer is needed, which effectively simplifies the basic structure and process flow of conventional LCMLA. Experiments indicated that a uniform LC alignment can be acquired in the EC-LCMLA cell by the SCG coupling alignment effect. The common optical properties including focal lengths and point spread function (PSF) were measured experimentally. Experiments demonstrated that the proposed EC-LCMLA has good focusing performance in the visible to near-infrared range. Moreover, the plenoptic imaging in Galilean mode was achieved by integrating the proposed EC-LCMLA with photodetectors. Digital refocusing was performed to obtain a rendering image of the target.

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Guevara De Jesus, Michael, Zhuyun Xiao, Maite Goiriena-Goikoetxea, Rajesh V. Chopdekar, Mohanchandra K. Panduranga, Paymon Shirazi, Adrian Acosta i in. "Magnetic state switching in FeGa microstructures". Smart Materials and Structures 31, nr 3 (25.01.2022): 035005. http://dx.doi.org/10.1088/1361-665x/ac46db.

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Abstract This work demonstrates that magnetoelectric composite heterostructures can be designed at the length scale of 10 µms that can be switched from a magnetized state to a vortex state, effectively switching the magnetization off, using electric field induced strain. This was accomplished using thin film magnetoelectric heterostructures of Fe81.4Ga18.6 on a single crystal (011) [Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32 (PMN-32PT) ferroelectric substrate. The heterostructures were tripped from a multi-domain magnetized state to a flux closure vortex state using voltage induced strain in a piezoelectric substrate. FeGa heterostructures were deposited on a Si-substrate for superconducting quantum interference device magnetometry characterization of the magnetic properties. The magnetoelectric coupling of a FeGa continuous film on PMN-32PT was characterized using a magneto optical Kerr effect magnetometer with bi-axial strain gauges, and magnetic multi-domain heterostructures were imaged using x-ray magnetic circular dichroism—photoemission electron microscopy during the transition to the vortex state. The domain structures were modelled using MuMax3, a micromagnetics code, and compared with observations. The results provide considerable insight into designing magnetoelectric heterostructures that can be switched from an ‘on’ state to an ‘off’ state using electric field induced strain.

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HE, CHENG, LIANG LIN, XIAO-CHEN SUN, XIAO-PING LIU, MING-HUI LU i YAN-FENG CHEN. "TOPOLOGICAL PHOTONIC STATES". International Journal of Modern Physics B 28, nr 02 (15.12.2013): 1441001. http://dx.doi.org/10.1142/s021797921441001x.

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As exotic phenomena in optics, topological states in photonic crystals have drawn much attention due to their fundamental significance and great potential applications. Because of the broken time-reversal symmetry under the influence of an external magnetic field, the photonic crystals composed of magneto-optical materials will lead to the degeneracy lifting and show particular topological characters of energy bands. The upper and lower bulk bands have nonzero integer topological numbers. The gapless edge states can be realized to connect two bulk states. This topological photonic states originated from the topological property can be analogous to the integer quantum Hall effect in an electronic system. The gapless edge state only possesses a single sign of gradient in the whole Brillouin zone, and thus the group velocity is only in one direction leading to the one-way energy flow, which is robust to disorder and impurity due to the nontrivial topological nature of the corresponding electromagnetic states. Furthermore, this one-way edge state would cross the Brillouin center with nonzero group velocity, where the negative-zero-positive phase velocity can be used to realize some interesting phenomena such as tunneling and backward phase propagation. On the other hand, under the protection of time-reversal symmetry, a pair of gapless edge states can also be constructed by using magnetic–electric coupling meta-materials, exhibiting Fermion-like spin helix topological edge states, which can be regarded as an optical counterpart of topological insulator originating from the spin–orbit coupling. The aim of this article is to have a comprehensive review of recent research literatures published in this emerging field of photonic topological phenomena. Photonic topological states and their related phenomena are presented and analyzed, including the chiral edge states, polarization dependent transportation, unidirectional waveguide and nonreciprocal optical transmission, all of which might lead to novel applications such as one-way splitter, optical isolator and delay line. In addition, the possible prospect and development of related topics are also discussed.

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Leisegang, Tilmann, Bianca Störr, Erik Mehner, Sven Jachalke, Charaf Cherkouk, Matthias Zschornak, Hartmut Stöcker, Mateo Urena, Ulrike Wunderwald i Dirk Meyer. "Pyroelectric Crystals: Structure, Properties and Applications". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C362. http://dx.doi.org/10.1107/s2053273314096375.

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As defined by the IUCr, a material is a crystal if it has essentially a sharp diffraction pattern. Crystalline materials are wide spread in our today's life. More than 98 % of the solid fraction of the earth comprises crystalline matter, most of which are oxides. Single-crystals in particular are the basis for many applications – lasers, LEDs, sensors, etc. – and play an important role in fundamental research – for instance in materials science. The discipline that elucidates the impact of the crystal structure on the physical properties of particularly crystalline materials – crystallography – is of specific importance for the design of new materials. Moreover, crystallography can be utilized to establish new concepts and thus may contribute solving today's challenges in science and technology. Several technologies exist for the conversion of electric energy into, e. g. heat, light and motion or vice versa. In this context, this work highlights an approach based on the crystal coupling phenomenon pyroelectricity that can be adopted for energy conversion concepts. By means of pyroelectric crystals, waste heat can be converted into surface charges, which provide a manifold of applications. First, a comprehensive overview of more than 3000 known pyroelectric materials is given, including a categorization in terms of properties and crystallographic characteristics. In order to provide a high pyroelectric coefficient at certain temperatures, taking economic, ecologic and further material properties into account, promising materials are suggested and verified by a computer controlled thermal/electrical stimulation set-up. Several possible applications as, for instance, disinfection [1], and anti-icing are presented. Finally, an approach to convert waste heat into chemical energy, i. e. the generation of hydrogen, is introduced.

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Sun, Fei, Tingfeng Ma, Pengfei Kang, Yuming Yao, Ning Gan, Lili Yuan, Wenhui Hu, Iren Kuznetsova i Ilya Nedospasov. "Pure- and Pseudo-Lateral-Field-Excitation Characteristics of Relaxor Ferroelectric Single Crystal PMN-PT". Micromachines 14, nr 6 (28.05.2023): 1136. http://dx.doi.org/10.3390/mi14061136.

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The relaxor ferroelectric single crystal (1−x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) has high piezoelectric constants, and thus has a good application prospect in the field of highly sensitive piezoelectric sensors. In this paper, for relaxor ferroelectric single crystal PMN-PT, the bulk acoustic wave characteristics on pure- and pseudo-lateral-field-excitation (pure- and pseudo-LFE) modes are investigated. LFE piezoelectric coupling coefficients and acoustic wave phase velocities for PMN-PT crystals in different cuts and electric field directions are calculated. On this basis, the optimal cuts of pure-LFE and pseudo-LFE modes of relaxor ferroelectric single crystal PMN-PT are obtained, namely, (zxt)45° and (zxtl)90°/90°, respectively. Finally, finite element simulations are carried out to verify the cuts of pure-LFE and pseudo-LFE modes. The simulation results show that the PMN-PT acoustic wave devices in pure-LFE mode have good energy-trapping effects. For PMN-PT acoustic wave devices in pseudo-LFE mode, when the device is in air, no obvious energy-trapping emerges; when the water (as a virtual electrode) is added to the surface of the crystal plate, an obvious resonance peak and the energy-trapping effect appears. Therefore, the PMN-PT pure-LFE device is suitable for gas-phase detections. While the PMN-PT pseudo-LFE device is suitable for liquid-phase detections. The above results verify the correctness of the cuts of the two modes. The research results provide an important basis for the development of highly sensitive LFE piezoelectric sensors based on relaxor ferroelectric single crystal PMN-PT.

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Sinyavsky, Nicolay, Irina Korneva, Michał Ostafin, Bolesław Nogaj i Mariusz Maćkowiak. "Two-Dimensional Nutation NQR Broad-Line Spectra in Oriented Samples". Zeitschrift für Naturforschung A 61, nr 9 (1.09.2006): 499–504. http://dx.doi.org/10.1515/zna-2006-0908.

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The NQR nutation method to determine the electric field gradient asymmetry parameter η in systems, where the resonance line is so broad that the radio frequency field can excite only a portion of the nuclear spins, is presented. In this situation, the recently developed spectroscopic methods are not applicable. Two-dimensional nutation NQR spectra of oriented powders are calculated and used to determine η at particular frequencies along a broad NQR line. The proposed method is useful for single crystals, oriented powders, glasses, and disordered systems even for small values of the asymmetry parameter. Therefore it can be used to evaluate fluctuations in η and the quadrupole coupling constant e2qQ due to inhomogeneities. We demonstrate the application of this method to oriented chalcogenide semiconducting glasses.

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Jiang, Bing, Yang Bai, Meicheng Li i Trevor Mwenya. "In situ observation of correlations between domain switching and crack propagation in BaTiO3 single crystals under coupling of mechanical and electric loads". Scripta Materialia 70 (styczeń 2014): 47–50. http://dx.doi.org/10.1016/j.scriptamat.2013.09.015.

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Zheng, Ming, Qiu-Xiang Zhu, Xue-Yan Li, Ming-Min Yang, Yu Wang, Xiao-Min Li, Xun Shi, Hao-Su Luo i Ren-Kui Zheng. "Electric-field-controlled interface strain coupling and non-volatile resistance switching of La1-xBaxMnO3 thin films epitaxially grown on relaxor-based ferroelectric single crystals". Journal of Applied Physics 116, nr 11 (21.09.2014): 113911. http://dx.doi.org/10.1063/1.4896172.

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Demirci, E., J. de Rojas, A. Quintana, I. Fina, E. Menéndez i J. Sort. "Voltage-driven strain-mediated modulation of exchange bias in Ir₂₀Mn₈₀/Fe₈₀Ga₂₀/Ta/⟨011⟩-oriented PMN-32PT heterostructures". Applied Physics Letters 120, nr 14 (4.04.2022): 142406. http://dx.doi.org/10.1063/5.0091231.

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Manipulation of exchange bias with electric field is appealing to boost energy efficiency in spintronic devices. Here, this effect is shown at room temperature in Ir20Mn80/Fe80Ga20/Ta layers grown onto ⟨011⟩-oriented PMN-32PT single crystals. After magnetic field-cooling (FC) along the [01-1] and [100] in-plane directions of PMN-32PT and upon allowing the system to relax through consecutive hysteresis loops (training effect), the exchange bias field (HEB) is measured under the action of voltage (out-of-plane poling). Depending on the applied voltage (magnitude and sign), HEB can either increase or decrease with respect to its value at 0 V. The relative variations of HEB are 24% and 5.5% after FC along the [01-1] and [100] directions, respectively. These results stem from strain-mediated magnetoelectric coupling. The applied electric field causes changes in the coercivity and the squareness ratio of the films, suggesting a reorientation of the effective magnetic easy axis in Fe80Ga20. However, larger HEB values are observed when the squareness ratio is lower. It is claimed that the effect of voltage is equivalent to an in-plane component of an applied magnetic field oriented perpendicular to the cooling field direction. Perpendicular in-plane magnetic fields have been shown to induce an increase in exchange bias in some ferromagnetic/antiferromagnetic systems due to partial recovery of the untrained antiferromagnetic state. Remarkably, here, this effect is directly induced with voltage, therefore enhancing energy efficiency.

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Wang, Zehuan, Shiyuan Liu, Zhengbao Yang i Shuxiang Dong. "Perspective on Development of Piezoelectric Micro-Power Generators". Nanoenergy Advances 3, nr 2 (4.04.2023): 73–100. http://dx.doi.org/10.3390/nanoenergyadv3020005.

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Anthropogenetic environmental deterioration and climate change caused by energy production and consumption pose a significant threat to the future of humanity. Renewable, environmentally friendly, and cost-effective energy sources are becoming increasingly important for addressing future energy demands. Mechanical power is the most common type of external energy that can be converted into useful electric power. Because of its strong electromechanical coupling ability, the piezoelectric mechanism is a far more successful technique for converting mechanics energy to electrical energy when compared to electrostatic, electromagnetic, and triboelectric transduction systems. Currently, the scientific community has maintained a strong interest in piezoelectric micro-power generators because of their great potential for powering a sensor unit in the distributed network nodes. A national network usually has a large mass of sensor units distributed in each city, and a self-powered sensor network is eagerly required. This paper presents a comprehensive review of the development of piezoelectric micro-power generators. The fundamentals of piezoelectric energy conversion, including operational modes and working mechanisms, are introduced. Current research progress in piezoelectric materials including zinc oxide, ceramics, single crystals, organics, composite, bio-inspired and foam materials are reviewed. Piezoelectric energy harvesting at the nano- and microscales, and its applications in a variety of fields such as wind, liquid flow, body movement, implantable and sensing devices are discussed. Finally, the future development of multi-field coupled, hybrid piezoelectric micropower generators and their potential applications are discussed.

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ALEXANDRU, Maria-Gabriela, Diana VISINESCU, Nadia MARINO, Giovanni De MUNNO, Francesc LLORET, Miguel JULVE i Marius ANDRUH. "Heterometallic supramolecular architectures constructed from cyanido-based [CoIII(AA)(CN)4]- building-blocks (AA = 1,10-phenantroline and 2,2’-bipyridine)". Revue Roumaine de Chimie 66, nr 3 (2021): 243–54. http://dx.doi.org/10.33224/rrch.2021.66.3.04.

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A neutral, mixed-valence cyanido-bridged {Co2IICo2III} complex, with formula {[CoII2(L)(MeOH)2][CoIII(phen)(CN)4]2}·2H2O·0.5MeOH (1), and a cyanido-based ionic compound, with formula [MnII(MAC)(H2O)2][CoIII(bipy)(CN)4]2·3H2O (2) were obtained by reacting the heteroleptic Ph4P[CoIII(AA)(CN)4] building-block [AA = 1,10-phenanthroline, phen, (1) and 2,2’-bipyridine, bipy, (2)] with the dinuclear {Co2IIL}2+ (1) and mononuclear {MnII(MAC)}2+ (2) precursors, respectively [H2L = macrocyclic Schiff-base obtained by condensation of 2,6-diformyl-p-cresol with 1,3-diaminopropane and MAC = 2,13-dimethyl-3,6,9,12,18-pentaazabicyclo-[12.3.1]octadeca-(18),2,12,14,16-pentaene]. The structures of 1 and 2 were determined by X-ray diffraction on single crystals. 1 is a neutral tetranuclear homometallic compound where two peripheral [CoIII(phen)(CN)4]- entities which act as end-cap ligands through one of its four cyanide groups towards the inner double phenoxido-bridged [Co2II(L)(MeOH)2]2+ dinuclear unit. Both cobalt(III) and cobalt(II) ions are six-coordinate with two phenanthroline-nitrogen and four cyanide-carbon atoms (at CoIII) and two phenoxido-oxygens and two imino-nitrogen atoms from the Schiff-base ligand plus a methanol molecule and a cyanide-nitrogen atom (at CoII) building somewhat distorted octahedral surroundings. The value of the cobalt(II)×××cobalt(II) separation is 3.11 Å and that of the angle at the phenoxo bridge is 99.4°. Compound 2 is a heterobimetallic ionic salt which is made up of [CoIII(bipy)(CN)4]- anions and [Mn(MAC)(H2O)2]2+ cations. Each cobalt(II) in 1 is six-coordinated, in a distorted octahedral environment built by a bidentate bipy ligand and four monodentate cyanide groups whereas the manganese(II) ion is seven-coordinated with five nitrogen atoms of the MAC ligand and two water molecules describing a distorted pentagonal bipyramid surrounding. The cryomagnetic investigation of 1 in the temperature range 1.9-300 K reveals the occurrence of strong spin-orbit coupling effects and a relatively weak antiferromagnetic interaction between the high-spin cobalt(II) ions linked by the double phenoxido bridge . The nature and magnitude of the magnetic coupling in 1 compares well with those from previous magneto-structural studies on the CoII2O2 motifs where antiferromagnetic interactions result in the examples having values at the phenoxido angle larger than 99.7º with dihedral angles smaller than 35.3°.

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Bhoi, Krishnamayee, Dhiren K. Pradhan, K. Chandrakanta, Narendra Babu Simhachalam, A. K. Singh, P. N. Vishwakarma, A. Kumar, Philip D. Rack i Dillip K. Pradhan. "Investigations of room temperature multiferroic and magneto-electric properties of (1-Φ) PZTFT-Φ CZFMO particulate composites". Journal of Applied Physics 133, nr 2 (14.01.2023): 024101. http://dx.doi.org/10.1063/5.0120665.

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Multiferroic composites consisting of a single-phase multiferroic [0.6(PbZr0.53Ti0.47O3)-0.4(PbFe0.5Ta0.5)O3] as a matrix and a magnetostrictive phase (Co0.6Zn0.4Fe1.7Mn0.3O4) dispersed in the matrix are fabricated via hybrid synthesis technique. The structure and surface morphology studies using x-ray diffraction and field emission scanning electron microscopy techniques indicate the formation of 3-0 type particulate composites. Coexistence of soft-magnetic behavior and ferroelectric characteristics are confirmed for composites from magnetization vs magnetic field (M–H) and polarization vs electric field (P–E) measurements, respectively. Magneto-dielectric (MD) measurement shows significant changes in the dielectric properties with the application of a magnetic field, indicating the existence of strong MD behavior. The biquadratic nature of magneto-electric (ME) coupling is described by the Landau free energy equation arising from the strain transfer at the interfaces between the constituent phases. The direct magneto-electric voltage coefficient measurement also confirms very strong coupling between ferroelectricity and magnetism and supports the strain-mediated magneto-electric effect in composites. The Φ = 0.3 composite exhibits the maximum ME coefficient of 20.72 mV/cm Oe with MS = 24.62 emu/g, HC = 59.66 Oe, and piezoelectric coefficient value d33 = 19 pC/N. The strong magneto-electric effect along with low dielectric loss at room temperature in these composites suggests their suitability for multifunctional magneto-electric device applications such as magnetic sensors, etc.

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QIU, Z. Q., J. PEARSON i S. D. BADER. "SHORT-PERIOD OSCILLATIONS OF THE MAGNETIC COUPLING OF EPITAXIAL GROWN Fe/Mo/Fe SANDWICHES ON Mo(100)". Modern Physics Letters B 06, nr 14 (20.06.1992): 839–49. http://dx.doi.org/10.1142/s0217984992001691.

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Epitaxial Fe / Mo / Fe sandwiches grown onto a Mo (100) single crystal were characterized in situ by electron diffraction and the magneto-optic Kerr effect. The intervening Mo layer is wedge shaped to facilitate the study of the magnetic coupling between the two (14-monolayer thick) Fe films as a function of Mo thickness. The exchange coupling between the Fe films across Mo was found to exhibit oscillatory behavior between antiferromagnetic (AF) and ferromagnetic coupling with a periodicity of ~3 ML of Mo . The shape of the hysteresis loop of the AF-coupled samples was calculated from a simple model that reproduces most of the experimental features.

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23

Shu, Guo-Jiun, Pei-Chieh Wu i F. C. Chou. "The spin–orbit–phonon coupling and crystalline elasticity of LaCoO3 perovskite". RSC Advances 10, nr 70 (2020): 43117–28. http://dx.doi.org/10.1039/d0ra09675j.

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Considering the before and after phonon softening, the gap in a CoO₆-octahedral crystal electric fields (CEF) and the thermally activated spin gap, were observed of ∼0.5 meV and Q ∼ 25 meV in defect-free LaCoO₃ single crystal, respectively.

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24

Walker, H. C., F. Fabrizi, L. Paolasini, F. de Bergevin, J. Herrero-Martin, A. T. Boothroyd, D. Prabhakaran i D. F. McMorrow. "Femtoscale Magnetically Induced Lattice Distortions in Multiferroic TbMnO3". Science 333, nr 6047 (1.09.2011): 1273–76. http://dx.doi.org/10.1126/science.1208085.

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Magneto-electric multiferroics exemplified by TbMnO3 possess both magnetic and ferroelectric long-range order. The magnetic order is mostly understood, whereas the nature of the ferroelectricity has remained more elusive. Competing models proposed to explain the ferroelectricity are associated respectively with charge transfer and ionic displacements. Exploiting the magneto-electric coupling, we used an electric field to produce a single magnetic domain state, and a magnetic field to induce ionic displacements. Under these conditions, interference between charge and magnetic x-ray scattering arose, encoding the amplitude and phase of the displacements. When combined with a theoretical analysis, our data allow us to resolve the ionic displacements at the femtoscale, and show that such displacements make a substantial contribution to the zero-field ferroelectric moment.

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25

Tanigaki, M., S. Takeda, K. Matsuta, Y. Matsumoto, T. Minamisono, H. Akai, K. Sato i in. "NMR Detection of Oxygen Isotopes in TiO2 Single Crystal". Zeitschrift für Naturforschung A 53, nr 6-7 (1.07.1998): 305–8. http://dx.doi.org/10.1515/zna-1998-6-708.

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Abstract We studied the electric quadrupole interactions of Oxygen isotopes in a TiO2 single crystal. For 13O and 19O nuclei, quadrupole coupling constants were measured by the β-NMR technique, and for the 17O nucleus the FT-NMR technique was utilized. We synthesized a TiO2 single crystal which was enriched in 17O up to 5 atom % to observe NMR signals without any perturbations from impurities. Using the known quadrupole moment of 17O, EFGs at an O site in TiO2 and the quadrupole moments of 13O and 19O were determined.

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26

Su, Gang. "Crystal Field Analysis of the Magnetization Curves of HoFe₁₁Ti under High Pressure". Advanced Materials Research 818 (wrzesień 2013): 72–76. http://dx.doi.org/10.4028/www.scientific.net/amr.818.72.

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The crystalline electric field parameters Anmfor HoFe11Ti under different pressures were evaluated by fitting calculations to the magnetization curves measured on the single crystals at several temperatures. It was found that magneto-crystalline anisotropy has been changed by high pressure and the Anmfor HoFe11Ti under high pressures are strikingly different from Anmfor the corresponding HoFe11Ti H with interstitial hydrogen atom.

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27

Cao, Yiming, Qianfeng Zhuang, Shengxian Wei, Xunqing Yin, Hongwei Liu, Yuanlei Zhang, Yanru Kang i in. "Evidence of magneto-structural coupling during the spin reorientation process in TmFeO3 single crystal". Journal of Magnetism and Magnetic Materials 523 (kwiecień 2021): 167626. http://dx.doi.org/10.1016/j.jmmm.2020.167626.

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Yevstafyev, O., V. Preobrazhensky, P. Pernod i V. Berzhansky. "Three wave coupling and explosive instability of magneto-elastic excitations in FeBO3 single crystal". Journal of Magnetism and Magnetic Materials 323, nr 11 (czerwiec 2011): 1568–73. http://dx.doi.org/10.1016/j.jmmm.2011.01.020.

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29

Sato, K., S. Takeda, S. Fukuda, T. Minamisono, M. Tanigaki, T. Miyake, Y. Maruyama, K. Matsuta, M. Fukuda i Y. Nojiri. "FT-NMR Detection of 45Sc, 49Ti and 93Nb in TiO2 Single Crystal". Zeitschrift für Naturforschung A 53, nr 6-7 (1.07.1998): 549–51. http://dx.doi.org/10.1515/zna-1998-6-745.

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Abstract In order to determine the electric quadrupole moment of the short-lived β-emitter 41Sc from the quadrupole coupling constant in TiO2 , we measured the field gradient by detecting the Fourier-Transformed-NMR of stable isotope 45Sc doped in TiO2. Also, in order to study the electronic structure of impurities systematically, EFGs were measured for 45Sc, 49Ti and 93Nb in a TiO2 ingle single crystal.

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30

Terao, Hiromitu, Tsutomu Okuda, Sachiyo Uyama, Hisao Negita, Shi-qi Dou, Hartmut Fuess i Alarich Weiss. "Crystal Structure Refinement and Single Crystal 81Br Zeeman NQR Study of KHgBr3· H2O". Zeitschrift für Naturforschung A 51, nr 12 (1.12.1996): 1197–202. http://dx.doi.org/10.1515/zna-1996-1209.

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Abstract Three 81Br NQR resonance lines of KHgBr3 ·H2O were detected between 77 K and room temperature. From the Zeeman effect measurement on a single crystal the nuclear quadrupole coupling constants (e2qQ/h) and the asymmetry parameters (ƞ) were obtained, which are 228.42 MHz and 0.005, 226.24 MHz and 0.005, and 108.76 MHz and 0.465 for e2qQ/h and ƞ at 295 K, respectively. Large deviations of the observed directions of electric field gradient tensors from the directions expected from previous X-ray results have been found. With the present X-ray redetermination, 81Br NQR and structure are in good agreement. The structure and bonding in the compound are discussed.

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31

Brinkmann, Andreas, i Mattias Edén. "Estimating internuclear distances between half-integer quadrupolar nuclei by central-transition double-quantum sideband NMR spectroscopy". Canadian Journal of Chemistry 89, nr 7 (lipiec 2011): 892–99. http://dx.doi.org/10.1139/v11-020.

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We demonstrate the estimation of homonuclear dipolar couplings, and thereby internuclear distances, between half-integer spin quadrupolar nuclei by central-transition (CT) double-quantum (2Q) sideband nuclear magnetic resonance (NMR) spectroscopy. It is shown that the rotor-encoded sideband amplitudes from CT 2Q coherences in the indirect dimension of the two-dimensional NMR spectrum are sensitive probes of the magnitude of the homonuclear dipolar coupling, but are significantly less affected by other NMR parameters such as the magnitudes and orientations of the electric field gradient tensors. Experimental results of employing the [Formula: see text] recoupling sequence to the 11B spin pair of bis(catecholato)diboron resulted in an estimation of the internuclear B–B distance as (169.6 ± 3) pm, i.e., with a relative uncertainty of ±2%, and in excellent agreement with the distance of 167.8 pm determined by single-crystal X-ray diffraction.

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32

Lee, Yea-Lee, Hee Chul Park, Jisoon Ihm i Young-Woo Son. "Manifestation of axion electrodynamics through magnetic ordering on edges of a topological insulator". Proceedings of the National Academy of Sciences 112, nr 37 (31.08.2015): 11514–18. http://dx.doi.org/10.1073/pnas.1515664112.

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Because topological surface states of a single-crystal topological insulator can exist on all surfaces with different crystal orientations enclosing the crystal, mutual interactions among those states contiguous to each other through edges can lead to unique phenomena inconceivable in normal insulators. Here we show, based on a first-principles approach, that the difference in the work function between adjacent surfaces with different crystal-face orientations generates a built-in electric field around facet edges of a prototypical topological insulator such as Bi2Se3. Owing to the topological magnetoelectric coupling for a given broken time-reversal symmetry in the crystal, the electric field, in turn, forces effective magnetic dipoles to accumulate along the edges, realizing the facet-edge magnetic ordering. We demonstrate that the predicted magnetic ordering is in fact a manifestation of the axion electrodynamics in real solids.

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33

Bai, Gang, Qiyun Xie, Xueshi Qin, Jie Xu, Xiaobing Yan i Cunfa Gao. "A generalized thermodynamic frame of magneto-electric-caloric coupling effects of single phase epitaxial multiferroic thin films". Ferroelectrics 531, nr 1 (27.07.2018): 186–95. http://dx.doi.org/10.1080/00150193.2018.1497414.

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Zhao, Xiao Fang, i A. K. Soh. "Phase Field Simulation of Ferroelectrics with Cracks". Key Engineering Materials 462-463 (styczeń 2011): 710–15. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.710.

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By employing a dipole defect model, two-dimensional phase field simulations of domain switching in the crack tip vicinity of a crack embedded in a relaxor ferroelectric single crystal, which was subjected to mechanical loading and electric field, have been carried out. The interaction between the dipole defects and crack, the influence of the dipole defect concentration density on the switching process, and the coupling effect of mechanical stress and electric field on domain switching in the vicinity of the crack tip have been studied. Comparing the results obtained from relaxor ferroelectrics with those of normal ferroelectrics, the former showed that, due to the interaction between the dipole defects and crack, polarization switching in the vicinity of the crack tip was suppressed. Moreover, the coupling between applied mechanical stress and electric field can either promote or suppress domain switching in the vicinity of a crack.

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Zhao, Zeen, Yecheng Ding, Xuefeng Zhao, Yaojin Wang, Ben Xu, Guanghua Liu, Guoliang Yuan i Jun-Ming Liu. "Photo-electro-striction in halide perovskite semiconductors". Applied Physics Letters 121, nr 4 (25.07.2022): 041102. http://dx.doi.org/10.1063/5.0099954.

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MAPbI3, MAPbBr3, and CsPbBr3 are excellent halide perovskite semiconductors with super long carrier diffusion length, long minority carrier lifetime, and large light absorption coefficient. Compared with the small intrinsic electrostriction, photocarriers induce a large photostriction in the surface layer. Furthermore, an electric field can efficiently separate the light excited electron–hole pairs, enhance photocarriers diffusion, and finally increase the crystal expansion, i.e., photo-electro-striction. For each crystal under 30 V/mm and in light with 450 nm wavelength and 840 mW/cm2, the photo-electro-striction is over four times of the pure electrostriction and is larger than the sum of photostriction and electrostriction. Most importantly, MAPbI3 single crystal shows a large photostriction of ∼0.35% and the photo-electro-striction of ∼0.64%. This work proves a very large photo-electro-striction as a result of the strong coupling among photocarriers, electric fields, and crystal lattices, which is important to develop semiconductor devices.

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36

Liu, Zheng, Ye-Xin Wang, Yu-Hui Fang, Si-Xue Qin, Zhe-Ming Wang, Shang-Da Jiang i Song Gao. "Electric field manipulation enhanced by strong spin-orbit coupling: promoting rare-earth ions as qubits". National Science Review 7, nr 10 (27.06.2020): 1557–63. http://dx.doi.org/10.1093/nsr/nwaa148.

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Abstract Quantum information processing based on magnetic ions has potential for applications as the ions can be modified in their electronic properties and assembled by a variety of chemical methods. For these systems to achieve individual spin addressability and high energy efficiency, we exploited the electric field as a tool to manipulate the quantum behaviours of the rare-earth ion which has strong spin-orbit coupling. A Ce:YAG single crystal was employed with considerations to the dynamics and the symmetry requirements. The Stark effect of the Ce3+ ion was observed and measured. When demonstrated as a quantum phase gate, the electric field manipulation exhibited high efficiency which allowed up to 57 π/2 operations before decoherence with optimized field direction. It was also utilized to carry out quantum bang-bang control, as a method of dynamic decoupling, and the refined Deutsch-Jozsa algorithm. Our experiments highlighted rare-earth ions as potentially applicable qubits because they offer enhanced spin-electric coupling which enables high-efficiency quantum manipulation.

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37

Evans, D. M., A. Schilling, Ashok Kumar, D. Sanchez, N. Ortega, R. S. Katiyar, J. F. Scott i J. M. Gregg. "Switching ferroelectric domain configurations using both electric and magnetic fields in Pb(Zr,Ti)O 3 –Pb(Fe,Ta)O 3 single-crystal lamellae". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, nr 2009 (28.02.2014): 20120450. http://dx.doi.org/10.1098/rsta.2012.0450.

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Thin single-crystal lamellae cut from Pb(Zr,Ti)O 3 –Pb(Fe,Ta)O 3 ceramic samples have been integrated into simple coplanar capacitor devices. The influence of applied electric and magnetic fields on ferroelectric domain configurations has been mapped, using piezoresponse force microscopy. The extent to which magnetic fields alter the ferroelectric domains was found to be strongly history dependent: after switching had been induced by applying electric fields, the susceptibility of the domains to change under a magnetic field (the effective magnetoelectric coupling parameter) was large. Such large, magnetic field-induced changes resulted in a remanent domain state very similar to the remanent state induced by an electric field. Subsequent magnetic field reversal induced more modest ferroelectric switching.

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38

Hajlaoui, Thameur, Catalin Harnagea i Alain Pignolet. "Magnetoelectric Coupling in Room Temperature Multiferroic Ba2EuFeNb4O15/BaFe12O19 Epitaxial Heterostructures Grown by Laser Ablation". Nanomaterials 13, nr 4 (17.02.2023): 761. http://dx.doi.org/10.3390/nano13040761.

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Multiferroic thin films are a promising class of multifunctional materials, since they allow the integration of multiple functionalities within a single device. In order to overcome the scarcity of single phase multiferroics, it is crucial to develop novel multiferroic heterostructures, combining good ferroelectric and ferromagnetic properties as well as a strong coupling between them. For this purpose, Ba2EuFeNb4O15/BaFe12O19 multiferroic magnetoelectric bilayers have been epitaxially grown on niobium doped SrTiO3 (100) single crystal substrates by pulsed laser deposition. The simultaneous presence of both ferroelectric and magnetic properties—due, respectively, to the Ba2EuFeNb4O15 and BaFe12O19 components—was demonstrated at room temperature, attesting the multiferroic nature of the heterostructure. More interestingly, a strong magnetoelectric coupling was demonstrated (i) by manipulating the ferroelectric properties via an external magnetic field, and conversely, (ii) by tuning the magnetic properties via an external electric field. This strong magnetoelectric coupling shows the high interdependence of both ferroic orders in the Ba2EuFeNb4O15/BaFe12O19 heterostructure, mediated by elastic (epitaxial) strain at the interfaces.

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39

Lucas, C. Robert, John M. D. Byrne, Julie L. Collins, Louise N. Dawe i David O. Miller. "Copper(II) complexes of open-chain thioether ligands terminated by salicylaldimine functionality*This article has a companion paper in this issue (doi: 10.1139/v11-081)." Canadian Journal of Chemistry 89, nr 10 (październik 2011): 1190–201. http://dx.doi.org/10.1139/v11-083.

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From 1,11-bis(salicylaldimine)-3,6,9-trithiaundecane (H2L1), 1,11-bis(salicylaldimine)-6-oxa-3,9-dithiaundecane (H2L2), and 1,8-bis(salicylaldimine)-3,6-dithiaundecane (H2L3), syntheses for [Cu(L1)]2 (I), Cu(L2)·CH3OH (II), Cu(L3) (III), [Cu(HL3)][CH3COO] (IV), [Cu(HL1-sal)]Cl2 (V), Cu4(L1)2Br4(H2O)2·2H2O (VI) and Cu2(L2)Br2·xH2O (VII) are described. Single crystal X-ray structural studies for I, III and VII are reported. Variable temperature magnetic susceptibility studies of I, VI and VII are discussed. The examination of VII represents the first magneto-structural study of a binuclear copper(II) species with NSO3Br coordination spheres. This study examines perturbation by one or more of the donor atoms so that none of the known magnetostructural models predicts the copper–copper coupling.

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40

Hashimoto, Masao, Norbert Weiden i Alarich Weiss. "The C—CI Bonds in α -2,4,6-tris(trichIoromethyl)-1,3,5-trioxane, α -Parachloral, (Cl3CCHO)3. A 35Cl-NQR Single Crystal Study". Zeitschrift für Naturforschung A 40, nr 4 (1.04.1985): 324–34. http://dx.doi.org/10.1515/zna-1985-0404.

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By single crystal 35C1-NQR Zeeman spectroscopy, the five independent 35Cl nuclear quadrupole coupling tensors in a-parachloral, (Cl3CCHO)3, have been studied at 24 ± 2 °C. The directions of the electric field gradient (EFG) tensor components have been determined. The principal axes Φ are within ± 0.8° parallel to the C-Cl bond directions found by X-ray diffraction. Very small asymmetry parameters in the range 0.002 ≦ η ≦ 0.046 are characteristic for the EFG tensors of chlorine atoms bound to carbon atoms in aliphatic systems. The five nuclear quadrupole coupling constants are in the range 76.752 ≦ e2qQh-1/MRz ≦ 78.155. The orientation of the principal axes Φxx and Φyy can be correlated to the molecular structure.

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41

Yu, Xinyue, Suna Zhuang, Jianfeng Chen, Zhi-Yuan Li i Wenyao Liang. "Reversible Conversion of Odd/Even One-Way Modes in Magneto-Optical Photonic Crystal Double-Channel Waveguides". Nanomaterials 12, nr 14 (17.07.2022): 2448. http://dx.doi.org/10.3390/nano12142448.

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We have studied the transmission properties of odd/even one-way modes and their reversible conversion in a double-channel waveguide consisting of two magneto-optical photonic crystals (MOPCs) sandwiched with Al2O3 PC. There exist two pairs of even and odd modes, i.e., M1(even)/M2(odd) or M3(odd)/M4(even) modes, for the double-channel waveguides with one- or two-stranded coupling layer of Al2O3 rods, respectively. Among them, the M1, M2, and M3 modes are caused by the weak coupling strength of two sub-waveguides, while the M4 mode results from the strong coupling effect and supports dispersionless slow-light propagation. Furthermore, we realize the reversible conversion between odd and even modes (i.e., between M1 and M2 modes, or M3 and M4 modes) in the one- or two-stranded structure, respectively, by adjusting the length and position of the perfect electric conductor (PEC) defect properly to cause the desired significant phase delay along the upper and lower equivalent transmission paths. Additionally, we find that the robustness of the M1 even mode is poor because of extra excitations of counter-propagation modes near the right Brillouin boundary, while the other three modes have extremely strong robustness against PEC defects and their one-way transmittances are nearly 100%. These results hold promise for many fields, such as slow-light modulation and the design of topological devices.

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42

Aboudi, Jacob. "The behavior of cracked multiferroic composites: Fully coupled thermo-electro-magneto-elastic analysis". Journal of Intelligent Material Systems and Structures 29, nr 15 (13.06.2018): 3037–54. http://dx.doi.org/10.1177/1045389x18781261.

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The response of cracked multiferroic composites that are subjected to thermo-electro-magneto-elastic loading is established by employing a two-scale analysis. To that end, the fully coupled constitutive and governing equations are utilized in the analysis. This form a generalization of a one-way thermal coupling analysis in which the electro-magneto-elastic field does not affect the thermal field. The micro-scale analysis is based on a micromechanical model which is capable of predicting the effective stiffness tensor of the undamaged multiferroic composite as well as the concentration tensors which enable the computation of the local field from the applied thermo-electro-magneto-elastic far-field. The macro-scale analysis provides the response of the cracked composite of periodic microstructure to the applied loading. It is based on the combined use of the representative cell method and the higher order theory. In the framework of the representative cell method, the problem for a periodic composite which is discretized into numerous identical cells is reduced to a problem of a single cell in the discrete Fourier transform domain. In the framework of the higher order theory, the governing equations and interfacial and periodic conditions formulated in the transform domain are solved by dividing the single cell into several subcells and imposing these conditions in an average (integral) sense. Results exhibit the responses caused by the application of mechanical, electric, magnetic, thermal, and heat flow loadings on two types of cracked periodically layered composites and provide comparisons between the predictions of the full and one-way thermal coupling analyses.

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43

Qian, MengLu, XianMei Wu, QingRui Yin, BingYing Zhang i John H. Cantrell. "Scanning electron acoustic microscopy of electric domains in ferroelectric materials". Journal of Materials Research 14, nr 7 (lipiec 1999): 3096–101. http://dx.doi.org/10.1557/jmr.1999.0415.

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Electric domains in single-crystal and polycrystalline barium titanate (BaTiO3) have been observed by use of scanning electron acoustic microscopy (SEAM). A model is presented of the SEAM signal generation, spatial resolution, and contrast mechanism associated with the imaging of electric domains in ferroelectric materials. The SEAM signal is found to depend directly on the sum of the piezoelectric coupling coefficient and spontaneous polarization of the domain, on the charge density of the electron beam interaction volume, and inversely on both the permittivity and the elastic constants of the material. Application of the model to BaTiO3 yields a contrast of roughly 3.5% from 90° domain structures and 6.8% from 180° domain structures.

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Bury, Peter, Marek Veveričík, František Černobila, Peter Kopčanský, Milan Timko i Vlasta Závišová. "Study of Structural Changes in Nematic Liquid Crystals Doped with Magnetic Nanoparticles Using Surface Acoustic Waves". Crystals 10, nr 11 (10.11.2020): 1023. http://dx.doi.org/10.3390/cryst10111023.

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The surface acoustic waves (SAWs) were used to study the effect of magnetic nanoparticles on nematic liquid crystal (NLC) behavior in weak magnetic and electric fields. The measurement of the attenuation of SAW propagating along the interface between piezoelectric substrate and liquid crystal is showed as an effective tool to study processes of structural changes. The magnetic nanoparticles Fe3O4 of nanorod shape and different low volume concentration were added to the NLC (4-(trans-4′-n-hexylcyclohexyl)-isothiocyanatobenzene (6CHBT)) during its isotropic phase. In contrast to undoped liquid crystals the distinctive different SAW attenuation responses induced by both magnetic and also electric fields in studied NLC samples were observed suggesting both structural changes and the orientational coupling between both magnetic and electric moments of nanoparticles and the director of the NLC molecules. Experimental measurements including the investigation under linearly increasing and/or jumped magnetic and electrical fields, respectively, as well as the investigation of temperature and time influences on structural changes were done. The investigation of the SAW anisotropy gives supplemental information about the internal structure of nanoparticles in investigated NLCs. In addition, some magneto-optical investigations were performed to support SAW results and study their stability and switching time. The analysis of observed SAW attenuation characteristics confirmed the role of concentration of magnetic nanoparticles on the resultant behavior of investigated NLC compounds. Obtained results are discussed within the context of previous ones. The theoretical background of the presented SAW investigation is introduced, too.

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Dyadkin, Vadim, i Dmitry Chernyshov. "Structural and Magnetic Chirality of Cu2OSeO3". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C1548. http://dx.doi.org/10.1107/s2053273314084514.

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We determine the chirality of the magnetic and crystal structures, respectively, for the magnetoelectric insulator Cu2OSeO3using small-angle diffraction of polarized neutrons and resonant contribution to X-ray single crystal diffraction of synchrotron radiation. This compound crystallizes in the P213 space group similar to other chiral but metallic magnets, such as MnSi, MnGe, MnSi1+xGex, Fe1+xCoxSi, Mn1+xFexSi, Mn1+xCoxSi, FeGe, Mn1+xFexGe. It has recently been shown that the structural and magnetic chiralities for metallic helimagnets are linked to each other [1], also in the so-called skyrmion phase [2]. Here we measure the spin chirality by comparing neutron scattering maps from Cu2OSeO3with the reference MnSi, which has left-handed magnetic spiral and absolute crystal structure denoted as left-handed [1]. Similar to the reference MnSi system, the crystallographic chirality of Cu2OSeO3is fixed on the basis of absolute structure determination taking into account the refinement of the Flack parameter. We find that the crystal and magnetic structures of Cu2OSeO3have the same chirality. The similar relationship is found for MnSi, Mn1+xFexSi, MnGe, while FeGe and Fe1+xCoxSi always show the opposite chiral correlation between magnetic and crystal structures. Notably, the relationship between two chiralities for Cu2OSeO3found in the experiment is opposite to that proposed from recent theoretical calculations [3], thus calling for a revision of the theory of possible microscopic mechanisms contributing to the phenomenological antisymmetric magneto-lattice coupling.

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You, Zhonglu, Yingying Luo, Susan Herringer, Yanmin Li, Silvio Decurtins, Karl W. Krämer i Shi-Xia Liu. "Formation of Tetranuclear Nickel(II) Complexes with Schiff-Bases: Crystal Structures and Magnetic Properties". Crystals 10, nr 7 (9.07.2020): 592. http://dx.doi.org/10.3390/cryst10070592.

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The cubane-type structure is a typical representative of tetranuclear coordination compounds. In this work, two anionic Schiff-base ligands, (L1)2− and (L2)2−, each offering an O^N^O coordination pocket, ligate four NiII ions into a [Ni4O4] cubane core. The ligands are H2L1 = 2−[[(3-ethoxy-2−hydroxyphenyl) methylene]amino]benzenemethanol and H2L2 = 2−[[(5-fluoro-2−hydroxyphenyl)methylene]amino]benzenemethanol. In both compounds, [Ni4(L1)4(EtOH)4] (1) and [Ni4(L2)4(MeOH)4] (2), alkoxy oxygens of the ligands act in a bridging μ3-O binding mode. Magnetic susceptibility and magnetization data for compounds 1 and 2 are presented. The Ni–O–Ni bond angles of the cubane core determined from single crystal X-ray diffraction data play a key role for a magneto-structural correlation. Dominant intracube ferromagnetic behavior is observed, and the coupling parameters were determined for both compounds, leading to nonzero spin ground states in accordance with the broadly accepted bond angle guideline.

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Sinusia Lozano, Miguel Sinusia, Laura Fernández-García, David López-Romero, Oliver A. Williams i Gonzalo F. Iriarte. "SAW Resonators and Filters Based on Sc0.43Al0.57N on Single Crystal and Polycrystalline Diamond". Micromachines 13, nr 7 (30.06.2022): 1061. http://dx.doi.org/10.3390/mi13071061.

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The massive data transfer rates of nowadays mobile communication technologies demand devices not only with outstanding electric performances but with example stability in a wide range of conditions. Surface acoustic wave (SAW) devices provide a high Q-factor and properties inherent to the employed materials: thermal and chemical stability or low propagation losses. SAW resonators and filters based on synthetized by reactive magnetron sputtering on single crystal and polycrystalline diamond substrates were fabricated and evaluated. Our SAW resonators showed high electromechanical coupling coefficients for Rayleigh and Sezawa modes, propagating at 1.2 GHz and 2.3 GHz, respectively. Finally, SAW filters were fabricated on /diamond heterostructures, with working frequencies above 4.7 GHz and ~200 MHz bandwidths, confirming that these devices are promising candidates in developing 5G technology.

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Li, Ting Xian, Ming Zhang, Zhou Hu, Kuo She Li, Dun Bo Yu i Hui Yan. "Preparation and Study of Strong Magnetoelectric Coupling on Multiferroic BaTiO₃/La_0.7Sr_0.3MnO₃ Bilayer Heterostructure". Advanced Materials Research 295-297 (lipiec 2011): 2015–19. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.2015.

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The BaTiO3/La0.7Sr0.3MnO3((BTO/LSMO) bilayer films had been epitaxially grown on (001) oriented LaAlO3 (LAO) single crystal substrate by using pulsed laser deposition technique,. The measurements of electric and magnetic properties showed that the bilayer heterostructure possessed low dielectric constant (εr=263), high ferromagnetic curie temperature (Tc=317K), and natural ferromagnetic and ferroelectric properties. The magnetoelectric (ME) voltage coefficient for the bilayer heterostructures at room temperature was around 140 mV/cm.Oe, which is one magnitude order higher than others. The interface coupling parameter k between ferromagnetic and ferroelectric layers was 0.68.

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Ni, Hao, Yi Wang, Feng Zhang, Jinwei Yang, Meng Wang, Xin Guo, Lu Chen, Shengnan Wang i Ming Zheng. "Electric-Field-Tunable Transport and Photo-Resistance Properties in LaMnO3−x/PMN-PT Heterostructures". Coatings 12, nr 7 (23.06.2022): 890. http://dx.doi.org/10.3390/coatings12070890.

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Multiferroic heterojunctions are promising for application in low-power storage and spintronics due to their magnetoelectric coupling properties. Controlling the magnetic and transport properties of magnetic materials by external stimuli and then realizing advanced devices constitute the key mission in this field. We fabricated a multiferroic heterostructure consisting of a ferroelectric single-crystal (001)-0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 substrate and an epitaxial 40 nm LaMnO3−x film. By applying dc electric fields to the ferroelectric substrate, the resistance and the photo-resistance of the LaMnO3−x film could be significantly modulated. With the electric field increasing from 0 to +4.8 kV/cm, the photo-resistance increased by ~4.1% at room temperature. The curve of photo-resistance versus the cycling electric field has a butterfly shape due to the piezoelectric strain effect. Using in situ X-ray diffraction measurements, the linear relationship of the strain and the electric field was quantitatively studied.

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Hou, Lei, Philippe Tamarat i Brahim Lounis. "Revealing the Exciton Fine Structure in Lead Halide Perovskite Nanocrystals". Nanomaterials 11, nr 4 (20.04.2021): 1058. http://dx.doi.org/10.3390/nano11041058.

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Lead-halide perovskite nanocrystals (NCs) are attractive nano-building blocks for photovoltaics and optoelectronic devices as well as quantum light sources. Such developments require a better knowledge of the fundamental electronic and optical properties of the band-edge exciton, whose fine structure has long been debated. In this review, we give an overview of recent magneto-optical spectroscopic studies revealing the entire excitonic fine structure and relaxation mechanisms in these materials, using a single-NC approach to get rid of their inhomogeneities in morphology and crystal structure. We highlight the prominent role of the electron-hole exchange interaction in the order and splitting of the bright triplet and dark singlet exciton sublevels and discuss the effects of size, shape anisotropy and dielectric screening on the fine structure. The spectral and temporal manifestations of thermal mixing between bright and dark excitons allows extracting the specific nature and strength of the exciton–phonon coupling, which provides an explanation for their remarkably bright photoluminescence at low temperature although the ground exciton state is optically inactive. We also decipher the spectroscopic characteristics of other charge complexes whose recombination contributes to photoluminescence. With the rich knowledge gained from these experiments, we provide some perspectives on perovskite NCs as quantum light sources.

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