Articles de revues : « Multiferroic Oxides - Magnetic Properties »

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Zhao, Li, Maria Teresa Fernández-Díaz, Liu Hao Tjeng et Alexander C. Komarek. « Oxyhalides : A new class of high-TC multiferroic materials ». Science Advances 2, n^o 5 (mai 2016) : e1600353. http://dx.doi.org/10.1126/sciadv.1600353.

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Magnetoelectric multiferroics have attracted enormous attention in the past years because of their high potential for applications in electronic devices, which arises from the intrinsic coupling between magnetic and ferroelectric ordering parameters. The initial finding in TbMnO3 has triggered the search for other multiferroics with higher ordering temperatures and strong magnetoelectric coupling for applications. To date, spin-driven multiferroicity is found mainly in oxides, as well as in a few halogenides. We report multiferroic properties for synthetic melanothallite Cu2OCl2, which is the first discovery of multiferroicity in a transition metal oxyhalide. Measurements of pyrocurrent and the dielectric constant in Cu2OCl2 reveal ferroelectricity below the Néel temperature of ~70 K. Thus, melanothallite belongs to a new class of multiferroic materials with an exceptionally high critical temperature. Powder neutron diffraction measurements reveal an incommensurate magnetic structure below TN, and all magnetic reflections can be indexed with a propagation vector [0.827(7), 0, 0], thus discarding the claimed pyrochlore-like “all-in–all-out” spin structure for Cu2OCl2, and indicating that this transition metal oxyhalide is, indeed, a spin-induced multiferroic material.

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Liu, Sheng, Feng Xiang, Yulan Cheng, Yajun Luo et Jing Sun. « Multiferroic and Magnetodielectric Effects in Multiferroic Pr2FeAlO6 Double Perovskite ». Nanomaterials 12, n^o 17 (30 août 2022) : 3011. http://dx.doi.org/10.3390/nano12173011.

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Single-phase multiferroics that allow the coexistence of ferroelectric and magnetic ordering above room temperature are highly desirable, and offer a fundamental platform for novel functionality. In this work, a double perovskite multiferroic Pr2FeAlO6 ceramic is prepared using a sol-gel process followed by a quenching treatment. The well-crystallized and purified Pr2FeAlO6 in trigonal structure with space group R3c is confirmed. A combination of the ferroelectric (2Pr = 0.84 μC/cm2, Ec = 7.78 kV/cm at an applied electric field of 20 kV/cm) and magnetic (2Mr = 433 memu/g, Hc = 3.3 kOe at an applied magnetic field of 1.0 T) hysteresis loops reveals the room-temperature multiferroic properties. Further, the magnetoelectric effect is observed from the measurements of magnetically induced dielectric response and polarization. The present results suggest a new complex oxide candidate for room-temperature multiferroic applications.

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Díaz-Moreno, Carlos A., Jorge A. López, Yu Ding, A. Hurtado Macias, Chunqiang Li et Ryan B. Wicker. « Multiferroic and Optical Properties of La0.05Li0.85NbO3 and LiNbO3 Nanocrystals ». Journal of Nanotechnology 2018 (3 septembre 2018) : 1–13. http://dx.doi.org/10.1155/2018/3721095.

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The chemistry and physics of surfaces is an increasingly important subject. The study of surfaces is the key of many important nanotechnological applications due to the understanding of phase transitions, electronic structure, and chemical bonding. In later years, exotic phenomena that jointly involve the magnetic and electrical conductivity properties have been discovered in oxides that contain magnetic ions. Moreover, the uses of magnetic oxides in electronic technology have become so important due to the miniaturization of devices and magnetic materials with dielectric properties or vice versa being required for inductors, information storage, thin films for high-density computer memories, microwave antireflection coatings, and permanent magnets for automobile ignitions among others. On the contrary, nanotechnology developments over 10 years or so have provided intensive studies in trying to combine properties such as ferroelectric, ferromagnetic, and optics in one single-phase nanoparticles or in composite thin films; this last effort has been recently known as multiferroic. Because of this, the resurgence of nanomaterials with multiferroic and optical properties is presented in this work of one single phase in lanthanum lithium niobate (La0.05Li0.85NbO3) and lithium niobate (LiNbO3) with ferromagnetic, ferroelectric, relaxor ferroelectricity, second harmonic generation, high-temperature ferromagnetic, and magnetoelectric properties.

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Xu, Xiaoshan, et Wenbin Wang. « Multiferroic hexagonal ferrites (h-RFeO3, R = Y, Dy-Lu) : a brief experimental review ». Modern Physics Letters B 28, n^o 21 (20 août 2014) : 1430008. http://dx.doi.org/10.1142/s0217984914300087.

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Hexagonal ferrites ( h - RFeO 3, R = Y , Dy - Lu ) have recently been identified as a new family of multiferroic complex oxides. The coexisting spontaneous electric and magnetic polarizations make h - RFeO 3 rare-case ferroelectric ferromagnets at low temperature. Plus the room-temperature multiferroicity and the predicted magnetoelectric effect, h - RFeO 3 are promising materials for multiferroic applications. Here we review the structural, ferroelectric, magnetic and magnetoelectric properties of h - RFeO 3. The thin film growth is also discussed because it is critical in making high quality single crystalline materials for studying intrinsic properties.

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Gareeva Z. V., Zvezdin A. K., Shulga N. V., Gareev T. T. et Chen X. M. « Mechanisms of magnetoelectric effects in oxide multiferroics with a perovskite praphase ». Physics of the Solid State 64, n^o 9 (2022) : 1324. http://dx.doi.org/10.21883/pss.2022.09.54175.43hh.

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Magnetoelectric effects are discussed in multiferroics with the perovskite structure: bismuth ferrite, rare-earth orthochromites, and Ruddlesden--Popper structures belonging to the trigonal, orthorhombic, and tetragonal syngonies. The influence of structural distortions on magnetic and ferroelectric properties is studied, possible magnetoelectric effects (linear, quadratic, inhomogeneous) in these materials are determined, and expressions for the linear magnetoelectric effect tensor are given. Macroscopic manifestations of the inhomogeneous magnetoelectric effect in multiferroic nanoelements are considered. Keywords: multiferroics, magnetoelectric effect, perovskites, symmetry.

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Cho, Jae-Hyeon, Ju-Hyeon Lee, Ji-Hun Park, Haeseong Jang, Hye-Lim Yu, Jongmoon Jang, Geon-Tae Hwang, Min Gyu Kim et Wook Jo. « Multiferroic properties in Fe-site engineered PbFe_1/2Nb_1/2O₃ with distinct antisymmetric spin interaction ». Applied Physics Letters 122, n^o 11 (13 mars 2023) : 112906. http://dx.doi.org/10.1063/5.0133678.

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Multiferroic Fe-site engineered lead iron niobate [Pb(Fe1/2Nb1/2)O3, PFN] was prepared by partially substituting Fe with Ni, Co, and Cr, which comprise distinct Bohr magnetons, to investigate the effect of the variation in spin configurations on magnetic and multiferroic properties. All the studied compositions exhibited a single-phase perovskite structure, wherein the lattice constant decreased with increasing substitutions. The inherent ferroelectric order was preserved when Ni or Co ions were introduced, while the introduction of Cr made the samples too lossy, which prevented the verification of the possible ferroelectricity. Substitution of Fe with different transition metals in PFN, which is originally paramagnetic at room temperature, resulted in oriented spin configurations that led to distinct magnetic orders: soft ferromagnetic, hard ferromagnetic, and antiferromagnetic orders for Ni, Co, and Cr, respectively. This distinction mainly stems from the interspin distance and the spin moment, both of which are important factors during the spin exchange interaction. The interspin distance of pristine and Cr-substituted PFN is too long and short, respectively, to induce ferromagnetic properties. Moreover, at room temperature, magnetic-field-dependent magnetoelectric coupling was observed only for the Ni- and Co-substituted PFN owing to their asymmetric spin configuration. This research could lead to a general method for modulating the magnetic properties of multiferroic perovskite oxides.

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Lorenz, Michael. « Pulsed laser deposition of functional oxides - towards a transparent electronics ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C1412. http://dx.doi.org/10.1107/s2053273314085878.

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Metal oxides, in particular with transition metals, show strong electronic correlations which determine a huge variety of electronic properties, together with other functionalities. For example, ZnO and Ga2O3 as wide-bandgap semiconductors have a high application potential as transparent functional layers in future oxide electronics [1-2]. Other oxides of current interest are ferrimagnetic spinels of the type MFe2O4 (M=Zn,Co,Ni), see K. Brachwitz et al. Appl. Phys. Lett. 102, 172104 (2013), or highly correlated iridate films, see M. Jenderka et al. Phys. Rev. B 88, 045111 (2013). Furthermore, combinations of ferroelectric and magnetic oxides in multiferroic composites and multilayers show promising magnetoelectric coupling. For the exploratory growth of the above mentioned novel oxides into nm-thin films, pulsed laser deposition (PLD) appears as the method of choice because of its extremely high flexibility in terms of material and growth conditions, high growth rate and excellent structural properties [3]. This talk highlights recent developments of new functional oxides using unique large-area PLD processes running for more than two decades in the lab of the author [3].

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Masuda, Ryoji, Yoshio Kaneko, Yoshinori Tokura et Youtarou Takahashi. « Electric field control of natural optical activity in a multiferroic helimagnet ». Science 372, n^o 6541 (29 avril 2021) : 496–500. http://dx.doi.org/10.1126/science.aaz4312.

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Controlling the chiral degree of freedom in matter has long been an important issue for many fields of science. The spin-spiral order, which exhibits a strong magnetoelectric coupling, gives rise to chirality irrespective of the atomic arrangement of matter. Here, we report the resonantly enhanced natural optical activity on the electrically active magnetic excitation, that is, electromagnon, in multiferroic cupric oxide. The electric field control of the natural optical activity is demonstrated through magnetically induced chirality endowed with magnetoelectric coupling. These optical properties inherent to multiferroics may lead to optical devices based on the control of chirality.

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Pattanayak, Samita, R. N. P. Choudhary et Piyush R. Das. « Studies of electrical conductivity and magnetic properties of Bi1-xGdxFeO3 multiferroics ». Journal of Advanced Dielectrics 04, n^o 02 (avril 2014) : 1450011. http://dx.doi.org/10.1142/s2010135x14500118.

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The polycrystalline samples of Bi 1-x Gd x FeO 3 (x = 0, 0.1, and 0.2) multiferroic oxides have been synthesized by a solid-state reaction/mixed oxide technique. The preliminary X-ray structural analysis with room temperature diffraction data confirmed the formation of single-phase systems. Study of room temperature scanning electron micrograph (SEM) of the surface of the above samples exhibits a uniform distribution of plate- and rod-shaped grains throughout the sample surface with less porosity. The dielectric behavior of the materials was studied in a wide range of frequency (1 kHz–1 MHz) and temperature (30–400°C). The nature of temperature dependence of dc conductivity confirms the Arrhenius behavior of the materials. The frequency–temperature dependence of ac conductivity suggests that the material obeys Jonscher's universal power law. An increase in Gd -content results in the enhancement of spontaneous magnetization BiFeO 3 (BFO) due to the collapse of spin cycloid structure. The magnetoelectric coupling coefficient of BFO has been enhanced on Gd -substitution.

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Xu, Chengchao, Jun Li, Huanfang Tian, Zi-An Li, Huaixin Yang et Jianqi Li. « Flux Method Growth and Structure and Properties Characterization of Rare-Earth Iron Oxides Lu1−xScxFeO3 Single Crystals ». Crystals 12, n^o 6 (26 mai 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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Kumar, Ashok, Nora Ortega, Sandra Dussan, Shalini Kumari, Dilsom Sanchez, James Scott et Ram Katiyar. « Multiferroic Memory : A Disruptive Technology or Future Technology ? » Solid State Phenomena 189 (juin 2012) : 1–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.189.1.

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The term "Multiferroic" is coined for a material possessing at least two ferroic orders in the same or composite phase (ferromagnetic, ferroelectric, ferroelastic); if the first two ferroic orders are linearly coupled together it is known as a magnetoelectric (ME) multiferroic. Two kinds of ME multiferroic memory devices are under extensive research based on the philosophy of "switching of polarization by magnetic fields and magnetization by electric fields." Successful switching of ferroic orders will provide an extra degree of freedom to create more logic states. The "switching of polarization by magnetic fields" is useful for magnetic field sensors and for memory elements if, for example, polarization switching is via a very small magnetic field from a coil underneath an integrated circuit. The electric control of magnetization is suitable for nondestructive low-power, high-density magnetically read and electrically written memory elements. If the system possesses additional features, such as propagating magnon (spin wave) excitations at room temperature, additional functional applications may be possible. Magnon-based logic (magnonic) systems have been initiated by various scientists, and prototype devices show potential for future complementary metal oxide semiconductor (CMOS) technology. Discovery of high polarization, magnetization, piezoelectric, spin waves (magnon), magneto-electric, photovoltaic, exchange bias coupling, etc. make bismuth ferrite, BiFeO3, one of the widely investigated materials in this decade. Basic multiferroic features of well known room temperature single phase BiFeO3in bulk and thin films have been discussed. Functional magnetoelectric (ME) properties of some lead-based solid solution perovskite multiferroics are presented and these systems also have a bright future. The prospects and the limitations of the ME-based random access memory (MERAM) are explained in the context of recent discoveries and state of the art research.

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Skulski, Ryszard, Dariusz Bochenek, Przemysław Niemiec, Dagmara Brzezinska et Artur Chrobak. « Technology and Main Properties of PMN-PT-Ferrite Multiferroic Ceramic Composite Materials ». Advances in Science and Technology 98 (octobre 2016) : 3–8. http://dx.doi.org/10.4028/www.scientific.net/ast.98.3.

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In the presented work composite ferroelectric/ferrimagnetic ceramics have been obtained and described. The investigated material is based on PMN-PT powders and Ni-Zn ferrite powder. The Powders of ferroelectric component (i.e. (1–x)PMN-(x)PT with x from 0.25 to 0.40 with step 0.03 were synthesized using the sol-gel method. The magnetic component i.e. nickel-zinc ferrite was obtained from oxides using the classic method of obtaining ceramics. The compositions of PMN–PT used by us have rhombohedral or tetragonal symmetries, or belong to morphotropic region. The final ceramic composite samples were obtained using the classic method of ceramic technology with calcination route and final pressureless densification using free sintering. In this paper, XRD, EDS dielectric and magnetic properties have been investigated and described for the obtained composite ceramic samples.

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Cheng, Xiangyi, Xiaoxiong Wang, Hongshun Yang, Keqing Ruan et Xiaoguang Li. « Multiferroic properties of the layered perovskite-related oxide La6(Ti0.67Fe0.33)6O20 ». Journal of Materials Chemistry C 3, n^o 17 (2015) : 4482–89. http://dx.doi.org/10.1039/c5tc00188a.

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Sun, Shujie, et Xiaofeng Yin. « Progress and Perspectives on Aurivillius-Type Layered Ferroelectric Oxides in Binary Bi4Ti3O12-BiFeO3 System for Multifunctional Applications ». Crystals 11, n^o 1 (29 décembre 2020) : 23. http://dx.doi.org/10.3390/cryst11010023.

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Driven by potentially photo-electro-magnetic functionality, Bi-containing Aurivillius-type oxides of binary Bi4Ti3O12-BiFeO3 system with a general formula of Bin+1Fen−3Ti3O3n+3, typically in a naturally layered perovskite-related structure, have attracted increasing research interest, especially in the last twenty years. Benefiting from highly structural tolerance and simultaneous electric dipole and magnetic ordering at room temperature, these Aurivillius-phase oxides as potentially single-phase and room-temperature multiferroic materials can accommodate many different cations and exhibit a rich spectrum of properties. In this review, firstly, we discussed the characteristics of Aurivillius-phase layered structure and recent progress in the field of synthesis of such materials with various architectures. Secondly, we summarized recent strategies to improve ferroelectric and magnetic properties, consisting of chemical modification, interface engineering, oxyhalide derivatives and morphology controlling. Thirdly, we highlighted some research hotspots on magnetoelectric effect, catalytic activity, microwave absorption, and photovoltaic effect for promising applications. Finally, we provided an updated overview on the understanding and also highlighting of the existing issues that hinder further development of the multifunctional Bin+1Fen−3Ti3O3n+3 materials.

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Baghizadeh, Ali, Pegah Mirzadeh Vaghefi, Xing Huang, Jerome Borme, Bernardo Almeida, Andrei N. Salak, Marc‐Georg Willinger, Vitor B. Amaral et Joaquim M. Vieira. « Interplay of Magnetic Properties and Doping in Epitaxial Films of h‐REFeO 3 Multiferroic Oxides ». Small 17, n^o 11 (23 février 2021) : 2005700. http://dx.doi.org/10.1002/smll.202005700.

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Zhou, Ziyao, Qu Yang, Ming Liu, Zhiguo Zhang, Xinyang Zhang, Dazhi Sun, Tianxiang Nan, Nianxiang Sun et Xing Chen. « Antiferroelectric Materials, Applications and Recent Progress on Multiferroic Heterostructures ». SPIN 05, n^o 01 (mars 2015) : 1530001. http://dx.doi.org/10.1142/s2010324715300017.

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Antiferroelectric (AFE) materials with adjacent dipoles oriented in antiparallel directions have a double polarization hysteresis loops. An electric field (E-field)-induced AFE–ferroelectric (FE) phase transition takes place in such materials, leading to a large lattice strain and energy change. The high dielectric constant and the distinct phase transition in AFE materials provide great opportunities for the realization of energy storage devices like super-capacitors and energy conversion devices such as AFE MEMS applications. Lots of work has been done in this field since 60–70 s. Recently, the strain tuning of the spin, charge and orbital orderings and their interactions in complex oxides and multiferroic heterostructures have received great attention. In these systems, a single control parameter of lattice strain is used to control lattice–spin, lattice–phonon, and lattice–charge interactions and tailor properties or create a transition between distinct magnetic/electronic phases. Due to the large strain/stress arising from the phase transition, AFE materials are great candidates for integrating with ferromagnetic (FM) materials to realize in situ manipulation of magnetism and lattice-ordered parameters by voltage. In this paper, we introduce the AFE material and it's applications shortly and then review the recent progress in AFEs based on multiferroic heterostructures. These new multiferroic materials could pave a new way towards next generation light, compact, fast and energy efficient voltage tunable RF/microwave, spintronic and memory devices promising approaches to in situ manipulation of lattice-coupled order parameters is to grow epitaxial oxide films on FE/ferroelastic substrates.

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Algueró, Miguel, Rafael P. del Real, Harvey Amorín et Alicia Castro. « Coexisting magnetic orders and concomitant Morin-like transition and relaxor behavior in multiferroic Aurivillius Bi₄Ti_{3 − 2x}Nb_xFe_xO₁₂ compounds ». Applied Physics Letters 121, n^o 12 (19 septembre 2022) : 122904. http://dx.doi.org/10.1063/5.0097079.

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Aurivillius layered oxides with general formula (Bi2O2)(Am−1BmO3m+1) stand out among room-temperature magnetoelectric multiferroics for their large magnetization. However, despite extensive research, there is an obvious lack of understanding of their magnetism. The chemical design strategy for obtaining multiferroism involves the incorporation of M3+ magnetic cations at the B-site of well-known ferroelectric compounds such as Bi4Ti3O12 (m = 3). We report here a study of the magnetism and dielectric properties of Aurivillius Bi4Ti3 − 2xNbxFexO12 phases with x ≥ 1 up to 1.2, which correspond to magnetic cation fractions at the B site between 0.33 and 0.4 above the threshold for percolation. This is a three-layer system, less prone to the formation of intergrowths, which nominally contains Fe3+ as single magnetic species. Despite that, a rich phenomenology is uncovered. Coexisting magnetic orders are present in the Aurivillius compounds, and a Morin-like transition takes place at low temperatures. The dielectric characterization does not show any associated anomaly that could indicate a polymorphic phase transition but the appearance of relaxor-like characteristics. Possible scenarios are discussed, which involve the presence of Fe2+, cation partitioning between nonequivalent B-sites, and the development of polar nanodomains within a ferroelectric phase at a spin reorientation transition.

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Rudnev, V. S., N. I. Steblevskaya, K. N. Kilin, M. A. Medkov, I. A. Tkachenko, M. V. Belobeletskaya, M. V. Adigamova, I. V. Lukiyanchuk et P. M. Nedozorov. « EuFeO₃/TiO₂/Ti Composites : Formation, Composition, Magnetic and Luminescent Properties ». Solid State Phenomena 245 (octobre 2015) : 178–81. http://dx.doi.org/10.4028/www.scientific.net/ssp.245.178.

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Layered oxide coatings containing europium ferrite multiferroic have been synthesized on titanium plates through plasma electrolytic oxidation and extraction pyrolysis. The composites have weak ferromagnetic properties: the coercive force attains 45–78 Oe in the temperature range 3–340 K. Their luminescence properties are typical of inorganic materials with europium ions.

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Moustafa, A. M., S. A. Gad, G. M. Turky et L. M. Salah. « Structural, Magnetic, and Dielectric Spectroscopy Investigations of Multiferroic Composite Based on Perovskite–Spinel Approach ». ECS Journal of Solid State Science and Technology 11, n^o 3 (1 mars 2022) : 033008. http://dx.doi.org/10.1149/2162-8777/ac5c7d.

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Multiferroic composite materials with the nominal composition (La0.8Gd0.2FeO3)1−x(Mn0.5Cu0.5Fe2O4)x, x = 0.0≤x≤1 were prepared using the co-precipition method. XRD, FTIR and Raman were utilized to investigate the structure phase, microstructural characteristics, vibrational bands. The optical properties were analyzed; the VSM was used to investigate the magnetic properties of the composites. Broadband dielectric spectroscopy is employed to investigate the dielectric and electrical performance of the prepared multiferroic composites. Rietveld refinement of the XRD patterns confirmed the orthorhombic phase for lanthanum gadolinium iron oxide (La0.8Gd0.2FeO3) and cubic phase for manganese copper ferrite (Mn0.5Cu0.5Fe2O4). The crystallite size of LGFO phase pointed out that it increases with increasing the MCFO phase, while the microstrain found to decline. The FTIR results elucidated the tetrahedral and octahedral bands. The deduced optical properties revealed that the samples have optical energy gap in the range 4.18 −4.5 eV. The magnetic properties revealed that the composites exhibit typical ferromagnetic hysteresis loops, indicating the presence of ordered magnetic structure. The frequency dependence of permittivity ε′(f) and real part of complex conductivity, σ′(f) exhibits a development of a net of micro-capacitors like behavior that stores charge carriers.

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Nechache, Riad, Louis-Philippe Carignan, Lina Gunawan, Catalin Harnagea, Gianluigi A. Botton, David Ménard et Alain Pignolet. « Epitaxial thin films of multiferroic Bi2FeCrO6 with B-site cationic order ». Journal of Materials Research 22, n^o 8 (août 2007) : 2102–10. http://dx.doi.org/10.1557/jmr.2007.0273.

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Epitaxial thin films of Bi2FeCrO6 (BFCO) have been synthesized by pulsed laser deposition on SrRuO3 on (100)- and (111)-oriented SrTiO3 substrates. Detailed x-ray diffraction and cross-section transmission electron microscopy analysis revealed a double perovskite crystal structure of the BFCO epitaxial films very similar to that of BiFeO3 along with a particularly noteworthy Fe3+/Cr3+ cation ordering along the [111] direction. The films contain no detectable magnetic iron oxide impurities and have the correct cationic average stoichiometry throughout their thickness. They however exhibit a slight modulation in the Fe and Cr compositions forming complementary stripe patterns, suggesting minor local excess or depletion of Fe and Cr. The epitaxial BFCO films exhibit good ferroelectric and piezoelectric properties, in addition to magnetic properties at room temperature, as well as an unexpected crystallographic orientation dependence of their room-temperature magnetic properties. Our results qualitatively confirm the predictions made using the ab initio calculations: the double perovskite structure of BFCO films exhibit a Fe3+/Cr3+ cation ordering and good multiferroic properties, along with the unpredicted existence of magnetic ordering at room temperature.

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Watson, Carla, Tara Peña, Marah Abdin, Tasneem Khan et Stephen M. Wu. « Dynamic adhesion of 2D materials to mixed-phase BiFeO₃ structural phase transitions ». Journal of Applied Physics 132, n^o 4 (28 juillet 2022) : 045301. http://dx.doi.org/10.1063/5.0096686.

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Two-dimensional materials, such as transition metal dichalcogenides, have generated much interest due to their strain-sensitive electronic, optical, magnetic, superconducting, or topological properties. Harnessing control over their strain state may enable new technologies that operate by controlling these materials’ properties in devices such as straintronic transistors. Piezoelectric oxides have been proposed as one method to control such strain states on the device scale. However, there are few studies of how conformal 2D materials remain on oxide materials with respect to dynamic applications of the strain. Non-conformality may lead to non-optimal strain transfer. In this work, we explore this aspect of oxide-2D adhesion in the nanoscale switching of the substrate structural phase in thin 1T′-MoTe2 attached to a mixed-phase thin-film BiFeO3 (BFO), a multiferroic oxide with an electric-field induced structural phase transition that can generate mechanical strains of up to 2%. We observe that flake thickness impacts the conformality of 1T′-MoTe2 to structural changes in BFO, but below four layers, 1T′-MoTe2 fully conforms to the nanoscale BFO structural changes. The conformality of few-layer 1T′-MoTe2 suggests that BFO is an excellent candidate for deterministic, nanoscale strain control for 2D materials.

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Latushka, S. I., D. V. Zheludkevich, E. V. Budemko, K. N. Nekludov, M. V. Silibin et D. V. Karpinsky. « Crystal Structure and Magnetic Properties of Bi1-yBa(Sr)Fe1-yTiyO3 Solid Solutions ». Journal of Material Science and Technology Research 10 (29 août 2023) : 82–85. http://dx.doi.org/10.31875/2410-4701.2023.10.08.

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Abstract: Usages of various chemical substitution schemes of the initial multiferroic BiFeO3 can significantly reduce known drawbacks specific for the functional oxides based of iron ions and thus foster a creation of novel magnetoelectric compounds perspective for various technological applications. In the present study the co-doped compounds of the system Bi1-y(Ba1- xSrx)yFe1-yTiyO3 (x = 0.0 – 1.0; y ≤ 0.4) synthesized using sol-gel technique were analyzed focusing on the crystal structure stability and the correlation between the structure and magnetic properties. The concentration driven evolution of the crystal structure as well as the unit cell parameters were investigated based on the X-ray diffraction data, the correlation between the crystal structure and the magnetic properties of the compounds has been studied by magnetometry techniques. The compounds Bi1-y(Ba1- xSrx)yFe1-yTiyO3 with x = 0; y = ≤ 0.2 are characterized by single-phase rhombohedral structure, and increase in the dopant concentration to y = 0.4 leads to the stabilization of the pseudocubic phase. An increase in the Sr content leads to the phase transition in the compounds to the single phase state with the cubic structure which is accompanied by an increase in the value of the remanent magnetization.

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Awan, M. S., A. S. Bhatti, S. Qing et C. K. Ong. « Tailoring of Multiferroic Properties of BiFeO₃ Thin Films by Cation Substitution ». Key Engineering Materials 442 (juin 2010) : 102–8. http://dx.doi.org/10.4028/www.scientific.net/kem.442.102.

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Mn-doped multiferroic BiFeO3 (BFMO) thin films were deposited on LaNiO3(LNO)/SrTiO3(STO)/Si(100) substrates by pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) showed that films were bicrystalline single phase with (110) preferential orientation. Multiferroic top layer and oxide bottom electrode (LNO) epitaxially followed the buffer layer (STO). Oxygen partial pressure during deposition proved to be critical for phase formation, crystallinity and resistivity of the films. Atomic force microscopic (AFM) studies revealed the smooth, dense and crack free surfaces of the films. Cross-section view of the multilayers by field emission scanning electron microscope (FE-SEM) gave their thickness. Mn substitution resulted in the increase of magnetization saturation, coercive field and clarity of hysteresis loop. The magneto-electric (ME) effect was demonstrated by measuring the dielectric response in a varying magnetic field. Optimally deposited BFMO films show saturated P-E loop.

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Gomi, Manabu, K. Ban, Naoya Nishimura et Takeshi Yokota. « Magnetoelectric Effect in Multiferroic Perovskite-Oxide Composites ». Advances in Science and Technology 45 (octobre 2006) : 2514–19. http://dx.doi.org/10.4028/www.scientific.net/ast.45.2514.

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Magnetic, dielectric properties and magnetoelectric effect of ceramics with a composition of 0.9 BaTiO3-0.1 LaMnO3 have been investigated. X-ray diffraction measurements showed that the sintered ceramics are composites containing a small amount of (La, Ba)MnO3 phase in the BaTiO3 matrix. These composites were multiferroic, having ferromagnetic and ferroelectric Curie temperatures of 330 K and 392 K respectively. We found that the composite sintered at 1150 °C exhibits a reduction of spontaneous magnetization as large as 55 % at room temperature when an electric field of 1.4 KV/mm is applied. This reduction is probably ascribed to a change of hole concentration distribution in the precipitated ferromagnetic (La, Ba)MnO3 and the resultant decrease of ferromagnetic Curie temperature.

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Pandey, R. K., H. Stern, W. J. Geerts, P. Padmini, P. Kale, Jian Dou et R. Schad. « Room Temperature Magnetic-Semicondcutors in Modified Iron Titanates : Their Properties and Potential Microelectronic Devices ». Advances in Science and Technology 54 (septembre 2008) : 216–22. http://dx.doi.org/10.4028/www.scientific.net/ast.54.216.

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The phenomenal growths of information technology and related fields have warranted the development of new class of materials. Multifunctional oxides, magnetic-semiconductors, multiferroics and smart materials are just a few examples of such materials. They are needed for the development of novel technologies such as spintronics, magneto-electronics, radhard electronics, and advanced microelectronics. For these technologies, of particular interest are some solid solutions of ilmenite-hematite (IH) represented by (1-x) FeTiO3.xFe2O3 where x varies from 0 to 1; Mn-doped ilmenite (Mn+3-FeTiO3) and Mn-doped pseudobrookite, Mn+3-Fe2TiO5 (PsB). These multifunctional oxides are ferromagnetic with the magnetic Curie points well above the room temperature as well as wide bandgap semiconductors with band gap Eg > 2.5 eV. This paper outlines: (a) processing of device quality samples for structural, electrical and magnetic characterization, (b) fabrication and evaluation of an integrated structure for controlled magnetic switching, and (c) the response of the two terminal non-linear current-voltage (I-V) characteristics when biased by a dc voltage. Subsequently, we will identify a few microelectronic applications based on this class of oxides.

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Pulphol, Nattakarn, R. Muanghlua, Surasak Niemcharoen, Wisanu Pecharapa, Wanwilai C. Vittayakorn et Naratip Vittayakorn. « Magnetoelectric Properties of BaTiO₃– Co_0.5Ni_0.5Fe₂O₄ Composites Prepared by the Conventional Mixed Oxide Method ». Advanced Materials Research 802 (septembre 2013) : 22–26. http://dx.doi.org/10.4028/www.scientific.net/amr.802.22.

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Multiferroics, which display simultaneous ferrimagnetic and ferroelectric properties, have been interesting recently because of their potentially significant applications in multifunctional devices such as magnetic resonance, drug delivery, high-density data storage, ferrofluid technology, etc. Composites combining BaTiO3 with Co0.5Ni0.5Fe2O4 have influenced the interest of many researchers, due to their outstanding and distinguished character called magnetoelectric (ME). In this work, ferrimagnetic-ferroelectric composites of BaTiO3 nanopowder and Co0.5Ni0.5Fe2O4 nanopowders were prepared by a conventional mixed oxide method. The multiferroic ceramics were compounded with the formula, (1-x)BaTiO3-(x)Co0.5Ni0.5Fe2O4, in which x = 0, 0.05, 0.10, 0.20 and 0.35. All of the compositions were analyzed by an X-ray diffractometer (XRD) in order to reveal the phase of perovskite and spinal structure. Scanning electron microscopy (SEM) was used to examine the variation of morphology and grain size of the composited ceramics. The magnetism of all the ceramics was measured using a vibrating sample magnetometer (VSM). The results showed that microstructure and the amount of ferrite are related strongly with magnetization.

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Dash, Swagatika, R. N. P. Choudhary, Piyush R. Das et Ashok Kumar. « Structural, dielectric, and multiferroic properties of (Bi0.5K0.5)(Fe0.5Nb0.5)O3 ». Canadian Journal of Physics 93, n^o 7 (juillet 2015) : 738–44. http://dx.doi.org/10.1139/cjp-2014-0025.

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A polycrystalline sample of (Bi0.5K0.5)(Fe0.5Nb0.5)O3 was prepared using a mixed oxide at 1000 °C. The preliminary structural analysis using X-ray diffraction data of the compound indicates the formation of a single-phase rhombohedral structure similar to that of parent BiFeO3. Microstructural and elemental analysis using a scanning electron micrograph and energy-dispersive X-ray spectroscopy, respectively, were carried out at room temperature with higher magnification exhibiting a uniform distribution of grains and stoichiometry. The appearance of hysteresis loops (P–E) confirms the existence of ferroelectricity of the sample with a high remnant polarization of (2Pr) 17.76 μCcm−2. Using impedance spectroscopy, the electrical properties of the material were investigated at a wide range of temperature (25–500 °C) and frequencies (1 kHz – 1 MHz) suggesting dielectric non-Debye-type relaxation in the material. The nature of the Nyquist plot ([Formula: see text] ∼ [Formula: see text]) shows the dominance of the grain contribution in the impedance. The bulk resistance of the compound decreases with increasing temperature, like that of a semiconductor, which shows a negative temperature coefficient of resistance (NTCR) behavior. The frequency dependence of AC conductivity suggests that that the material obeys Jonscher’s power law. Magnetic hysteresis (M–H) loop shows very weak ferromagnetic behavior at room temperature.

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Wang, Ling, Tsukasa Katayama, Chaoyue Wang, Qin Li, Yun Shi, Yuqiang Fang, Fuqiang Huang et al. « Enhancement of room-temperature magnetization in GaFeO₃-type single crystals by Al and Sc doping ». AIP Advances 12, n^o 6 (1 juin 2022) : 065015. http://dx.doi.org/10.1063/5.0088234.

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GaFeO3-type oxides are promising multiferroic materials due to the coexistence of spontaneous magnetization and ferroelectric polarization properties at room temperature. As these ferroic properties feature a large anisotropy, single crystals are required. However, the magnetization of GaFeO3-type single crystals remains low at room temperature. In this study, we largely enhanced the magnetization at room temperature of GaFeO3-type single crystals by increasing the Fe content and co-doping Sc3+ and Al3+. Single crystals of Al xSc0.1− xGa0.6Fe1.3O3 ( x = 0.01–0.04) were prepared using the optical floating-zone method. The single crystals were rod-shaped, with a diameter and length of ∼6 mm and 7 cm, respectively. X-ray diffraction measurements confirmed the ferroelectric polarization of the crystals. In addition, they exhibited room-temperature ferrimagnetism, with Curie temperature in the range of 326–338 K; the crystals exhibit magnetic anisotropy along the a-axis. The magnetization of the single crystal at 300 K and 0.3 kOe was 13 emu g−1, which is over ten times larger than those of previously reported single crystals with GaFeO3-type crystal structure.

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García-Zaldívar, O., S. Díaz-Castañón, F. J. Espinoza-Beltran, M. A. Hernández-Landaverde, G. López, J. Faloh-Gandarilla et F. Calderón-Piñar. « BiFeO3 codoping with Ba, La and Ti : Magnetic and structural studies ». Journal of Advanced Dielectrics 05, n^o 04 (décembre 2015) : 1550034. http://dx.doi.org/10.1142/s2010135x15500344.

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Conventional solid state reaction method, from oxides and carbonates, was employed to prepare bismuth (Bi)-based multiferroic systems. The undoped BiFeO3 (BFO) and the codoped system with Ba, La and Ti (Bi[Formula: see text]BaxFe[Formula: see text]TiyO3, Bi[Formula: see text]BaxLazFe[Formula: see text]TiyO3) with x,y,[Formula: see text] were prepared stoichiometrically and sintered at two different temperatures. The structural and magnetic properties were investigated at room temperature. XRD measurements confirm the obtaining of the rhombohedral perovskite structure of the BFO family system. For the undoped system, some reflections of undesired phases are present for two different sintering temperatures, while for the doped system only one phase is present for both temperatures. The magnetic characterization at room temperature revealed remarkable differences between the ceramic samples. The results show that for undoped BFO system, spontaneous magnetization is not observed at room temperature. Nevertheless, in doped one, a well-defined ferromagnetic behavior is observed at room temperature, possible, due to the suppression of the spatially modulated spin structure of BFO promoted by the reduction of the rhombohedral distortion and the weakening of the Bi–O bonds. The XPS results confirm the presence of oxygen vacancies and the coexistence of Fe[Formula: see text] and Fe[Formula: see text] in all the studied samples. Calorimetric measurements reveal that the dopant incorporation has not a direct effect in Néel temperature but possibly yes in ferroelectric-paraelectric transition.

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Mun, Eundeok, Jason Wilcox, Jamie L. Manson, Brian Scott, Paul Tobash et Vivien S. Zapf. « The Origin and Coupling Mechanism of the Magnetoelectric Effect inTMCl2-4SC(NH2)2(TM= Ni and Co) ». Advances in Condensed Matter Physics 2014 (2014) : 1–4. http://dx.doi.org/10.1155/2014/512621.

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Most research on multiferroics and magnetoelectric effects to date has focused on inorganic oxides. Molecule-based materials are a relatively new field in which to search for magnetoelectric multiferroics and to explore new coupling mechanisms between electric and magnetic order. We present magnetoelectric behavior in NiCl2-4SC(NH2)2(DTN) and CoCl2-4SC(NH2)2(DTC). These compounds form tetragonal structures where the transition metal ion (Ni or Co) is surrounded by four electrically polar thiourea molecules [SC(NH2)2]. By tracking the magnetic and electric properties of these compounds as a function of magnetic field, we gain insights into the coupling mechanism by observing that, in DTN, the electric polarization tracks the magnetic ordering, whereas in DTC it does not. For DTN, all electrically polar thiourea molecules tilt in the same direction along thec-axis, breaking spatial-inversion symmetry, whereas, for DTC, two thiourea molecules tilt up and two tilt down with respect toc-axis, perfectly canceling the net electrical polarization. Thus, the magnetoelectric coupling mechanism in DTN is likely a magnetostrictive adjustment of the thiourea molecule orientation in response to magnetic order.

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Cortés Estay, Emilio A., Shyue P. Ong, Caroline A. Ross et Juan M. Florez. « Oxygen Deficiency and Migration-Mediated Electric Polarization in Magnetic Fe,Co-Substituted SrTiO3−δ ». Magnetochemistry 8, n^o 11 (1 novembre 2022) : 144. http://dx.doi.org/10.3390/magnetochemistry8110144.

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We use density functional theory (DFT) calculations to show that oxygen vacancies (vO) and mobility induce noncentrosymmetric polar structures in SrTi1−x−yFexCoyO3−δ (STFC, x=y=0.125) with δ={0.125,0.25}, enhance the saturation magnetization, and give rise to large changes in the electric polarization |ΔP|. We present an intuitive set of rules to describe the properties of STFC, which are based on the interplay between (Co/Fe)-vO defects, magnetic cation coordination, and topological vacancy disorder. STFC structures consist of layered crystals with sheets of linearly organized O4,5,6-coordinated Fe–Co pairs, sandwiched with layers of O5-coordinated Ti. (Co/Fe)-vO defects are the source of crystal distortions, cation off-centering and bending of the oxygen octahedra which, considering the charge redistribution mediated by vO and the cations’ electronegativity and valence states, triggers an effective electric polarization. Oxygen migration for δ=0.125 leads to |ΔP|>∼10 µC/cm2 due to quantum-of-polarization differences between δ=0.125 structures. Increasing the oxygen deficiency to δ=0.25 yields |ΔP|, the O migration of which resolved polarization for δ=0.25 is >∼3 µC/cm2. Magnetism is dominated by the Fe,Co spin states for δ=0.125, and there is a contribution from Ti magnetic moments (∼1 μB) for δ=0.25. Magnetic and electric order parameters change for variations of δ or oxygen migration for a given oxygen deficiency. Our results capture characteristics observed in the end members of the series SrTi(Co,Fe)O3, and suggest the existence of a broader set of rules for oxygen-deficient multiferroic oxides.

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Stojanovic, Nemanja, Aleksandra Kalezic-Glisovic, Aco Janicijevic et Aleksa Maricic. « Evolution of structural and functional properties of the Fe/BaTiO3 system guided by mechanochemical and thermal treatment ». Science of Sintering 52, n^o 2 (2020) : 163–76. http://dx.doi.org/10.2298/sos2002163s.

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Multiferroic systems are attractive to the researches worldwide due to diversity of existing applications, as well as possible novel ones. In order to contribute to understanding of the processes that take place within the structure of such a system, we subjected it to mechanochemical activation and thermal treatment. Powdery mixtures of iron and barium titanate in a mass ratio of 30% Fe and 70% BaTiO3 were activated in a planetary ball mill for time duration of 30 to 300 min and subsequently sintered at 1200?C in the atmosphere of air. During the activation the system undergoes structural phase transitions, whereby the content of iron and its oxides changes. The highest Fe content was observed in the sample activated for 270 min, with local maxima in crystallite size and microstrain values and a minimum in dislocation density. The complex dielectric permittivity changes in the applied radio frequency field, rangingfrom 176.9 pF/m in thesample activated for 90 min to 918.1 pF/m in the sample activated for 180 min. As the frequency of the field increases, an exponential decrease in the magnetic with a simultaneous increase in the electrical energy losses is noticeable. The system exhibits ferromagnetic resonance, whereby longer activation in the mill shifts the resonant frequency to higher values. Negative electrical resistance was observed in all analyzed samples. The activation time changes both the demagnetization temperature and the Curie temperature of the samples undergoing heating and cooling cycles in the external permanent magnetic field. Curie temperature is the highest in the sample activated for 240 min. Thermal treatment increases the initial magnetization of all samples, with the most pronounced increase of ~95% in the sample activated for 300 min.

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Kumari, Kalpana. « Magnetic and dielectric properties of Fe3BO6 nanoplates prepared through self-combustion method ». Journal of Advanced Dielectrics 07, n^o 06 (décembre 2017) : 1750043. http://dx.doi.org/10.1142/s2010135x17500436.

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In the present investigation, a facile synthesis method is explored involving a self-combustion of a solid precursor mixture of iron oxide Fe2O3 and boric acid (H3BO3) using camphor (C[Formula: see text]H[Formula: see text]O) as fuel in ambient air in order to form a single phase Fe3BO6 crystallites. X-ray diffraction (XRD), Field emission electron microscopy (FESEM), magnetic, and dielectric properties of as prepared sample are studied. From XRD pattern, a single phase compound is observed with an orthorhombic crystal structure (Pnma space group), with average crystallite size of 42[Formula: see text]nm. A reasonably uniform size distribution of the plates and self-assemblies is retained in the sample. A magnetic transition is observed in dielectric permittivity (at [Formula: see text]445[Formula: see text]K) and power loss (at [Formula: see text]435[Formula: see text]K) when plotted against temperature. A weak peak occurs near 330[Formula: see text]K due to the charge reordering in the sample. For temperatures above the transition temperature, a sharp increase of the dielectric loss is observed which occurs due to the presence of thermally activated charge carriers. A canted antiferromagnetic Fe[Formula: see text] ordering in a Fe3BO6 lattice with a localized charge surface layer is an apparent source of exhibiting a ferroelectric feature in this unique example of a centrosymmetric compound. An induced spin current over the Fe sites thus could give rise to a polarization hysteresis loop. Due to the presence of both ferromagnetic as well as polarization ordering, Fe3BO6 behaves like a single phase multiferroic ceramics.

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Delfard, Naimeh Badvi, Hamed Maleki, Asma Mohammadi Badizi et Majid Taraz. « Enhanced Structural, Optical, and Multiferroic Properties of Rod-Like Bismuth Iron Oxide Nanoceramics by Dopant Lanthanum ». Journal of Superconductivity and Novel Magnetism 33, n^o 4 (18 novembre 2019) : 1207–14. http://dx.doi.org/10.1007/s10948-019-05294-3.

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El Housni, I., N. El Mekkaoui, R. Khalladi, S. Idrissi, S. Mtougui, H. Labrim, S. Ziti et L. Bahmad. « The magnetic properties of the multiferroic transition metal oxide perovskite-type Pb(Fe1/2Nb1/2)O3 : Monte Carlo simulations ». Ferroelectrics 568, n^o 1 (3 novembre 2020) : 191–213. http://dx.doi.org/10.1080/00150193.2020.1834776.

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Wang, Zhe, Jie-Min Xu, Wen-Jun Wang, He-Xuan Li, You-Ming Zou, Lu Yu et Zhe Qu. « Electron spin resonance study of spin fluctuation in multiferroic MnSb2O6 ; ». Acta Physica Sinica 71, n^o 1 (2022) : 017501. http://dx.doi.org/10.7498/aps.71.20211465.

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The magnetic materials with a chiral crystallographic lattice have hold neither inversion center nor mirror plane, leading to the emergence of Dzyaloshinskii-Moriya interaction and exotic physical phenomena like skyrmion, multiferroicity, and chiral solition lattice. The trigonal oxide MnSb2O6 is recognized as a novel chiral-lattice helimagnet with unusual multiferroic properties, where magnetic field enables the selecting of a single ferroelectric domain and a slight tilting of field direction can trigger the reversal of electric polarization. Single crystal of MnSb2O6 is prepared by the flux method. The magnetic susceptibility at 2 K shows a linear field dependent behavior except in the low field region. The magnetization shows a deviation from linearity at around 0.2 T for H⊥c, while a step-like anomaly is observed at about 1 T for H//c, suggesting the domain selection and spin-flop transition, respectively. The electron spin resonance parameters, such as the resonance field, the g-factor and the linewidth ΔH, are obtained by performing single Lorentzian line. Interestingly, the resonance field shows a distinct, anisotropic temperature dependent behavior when further cooling, the resonance field shifts towards the lower field direction for H⊥c, while it shifts towards higher field direction for H//c. Excluding several mechanisms for this FM-like temperature dependent behavior of the resonance field, combining the ground state of spiral phase and its unique multiferroic properties, we suggest that the spiral magnetic structure of the ground state of MnSb2O6 forms a conical magnetic structure under external magnetic field. Based on this, we can speculate the variation of ferroelectric polarization intensity with moderate and higher magnetic field. Moreover, the critical fitting of the ESR linewidth gives an unusual small critical index, p = 0.49 for H⊥c and p = 0.54 for H//c, implying that the magnetism possesses a two-dimensional characteristic and competitive interaction.

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Singamaneni, Srinivasa Rao, J. T. Prater et J. Narayan. « Enhanced Coercivity in BiFeO3/SrRuO3heterostructures ». MRS Advances 1, n^o 9 (2016) : 597–602. http://dx.doi.org/10.1557/adv.2016.220.

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ABSTRACTTransition metal oxide thin film heterostructures have garnered increasing research interest in the last decade due to their multifunctional properties, such as ferromagnetism and ferroelectricity, which may be utilized in next generation device applications. Many previous works reported on the deposition of such structures on oxide substrates such as SrTiO3, which are not compatible with CMOS applications where Si(100) is the mainstay substrate material. BiFeO3(BFO) is a room temperature insulating ferroelectric and antiferromagnet, a well-known multiferroic material. SrRuO3(SRO) is a ferromagnetic metal with the Curie temperature (TC) of 165K. Unexpected properties emerge when these two dissimilar materials are conjoined. However, there has been no report on exploring the magnetic properties of BFO when it is in contact with SRO, and particularly when they are integrated with Si(100) substrates, which is the subject of present study. BFO/SRO thin films have been epitaxially grown on Si (100) substrates by introducing MgO/TiN epitaxial buffer layers using pulsed laser deposition. BFO thin films show room temperature ferroelectricity as observed from piezo force microscopy (PFM) measurements. The magnetic data collected from BFO thin films show typical antiferromagnetic features as expected. The TCof SRO in all the samples studied was found be ∼ 170K, close to the reported value of 165K. Interestingly, we have noticed that the coercive field of SRO layer increased from 4 kOe to 15 kOe (nearly fourfold) by reducing its thickness from 180 to 23nm, while keeping the thickness of BFO layer constant at 100nm. Pinning of Ru ions by ferroelectric domain walls in BFO, strong interfacial exchange coupling and SRO layer thickness could cause the observed enhancement in coercivity. Our near future work will address the precise underlying mechanisms in greater detail.

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Chen, Xuemei, Guangda Hu, Jing Yan, Xi Wang, Changhong Yang et Weibing Wu. « Enhanced multiferroic properties of (1 1 0)-oriented BiFeO3film deposited on Bi3.5Nd0.5Ti3O12-buffered indium tin oxide/Si substrate ». Journal of Physics D : Applied Physics 41, n^o 22 (23 octobre 2008) : 225402. http://dx.doi.org/10.1088/0022-3727/41/22/225402.

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Mazzoli, Claudio, et Paolo Ghigna. « Multiferroic Properties In Complex Oxides ». Current Inorganic Chemistry 3, n^o 1 (1 février 2013) : 70–74. http://dx.doi.org/10.2174/1877944111303010007.

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Kawaguchi, Shogo, Hiroki Ishibashi, Shigeo Mori, Jungeun Kim, Kenichi Kato, Masaki Takata, Hironori Nakao, Yuichi Yamasaki et Yoshiki Kubota. « Orbital Order and Structural Phase Transitions in Vanadium Spinel FeV2O4 ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C1358. http://dx.doi.org/10.1107/s2053273314086410.

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Orbital degrees of freedom plays an important role in condensed matter physics because it is strongly related with phase transitions and induces the fascinating physical properties. A spinel oxide FeV2O4is one of the peculiar examples because this compound has double orbital degrees of freedom at both Fe2+and V3+ions. Furthermore, this material represents exotic physical properties [1,2], i.e.; multiferroic, large magnetostriction, and successive structural transitions with decreasing temperature: cubic - tetragonal (c < a: tetraHT, 138K) - orthorhombic (orthoHT, 108 K) - tetragonal (c > a: tetraLT, 68 K). However, the origin of structural transitions and physical properties is controversial until now. In order to clarify the origin, we have performed synchrotron x-ray diffraction experiments at low temperatures at beamline BL02B2 (for the powder samples) in SPring-8 and BL-4C (for the single crystal) of the Photon Factory, KEK. Furthermore, we have carried out the magnetization and the specific heat measurements using polycrystalline samples and single crystal of FeV2O4. We have firstly found another orthorhombic phase (orthoLT) below 30 K in the polycrystalline sample of FeV2O4, shown in figure 1. The Rietveld analysis was performed, and the overall qualities of fittings were fairly good. In order to investigate the details of the orbital state of Fe2+and V3+in FeV2O4, we have performed the normal mode analysis, which is based on static displacements of the tetrahedron of FeO4and octahedron of VO6. In the orthoLT phase, we found the orbital order of Fe2+ions, which is mixture of 3z2-r2and y2-z2orbitals, without change of orbital order of V3+ions. This result indicates that the origin of the orthoLT phase is derived from the competition between cooperative Jahn-Teller effect and relativistic spin-orbit coupling of Fe2+ions. We also discuss the origins of the other phase transitions considering the orbital state of V3+and Fe2+ions, and then the orbital dilution effect, where the structural and magnetic properties are investigated by using powder samples substituted for Fe2+and V3+ions by other ions (Mn2+and Fe3+) with no orbital degrees of freedom.

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Tokura, Yoshinori, et Noriaki Kida. « Dynamical magnetoelectric effects in multiferroic oxides ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 369, n^o 1951 (28 septembre 2011) : 3679–94. http://dx.doi.org/10.1098/rsta.2011.0150.

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Multiferroics with coexistent ferroelectric and magnetic orders can provide an interesting laboratory to test unprecedented magnetoelectric (ME) responses and their possible applications. One such example is the dynamical and/or resonant coupling between magnetic and electric dipoles in a solid. As examples of such dynamical ME effects, (i) the multiferroic domain wall dynamics and (ii) the electric dipole active magnetic responses are discussed with an overview of recent experimental observations.

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QI, X. W., H. F. WANG, W. Q. HAN, P. H. WANG-YANG, J. ZHOU et Z. X. YUE. « MAGNETIC PROPERTIES OF MULTIFERROIC MATERIALS ». International Journal of Modern Physics B 23, n^o 17 (10 juillet 2009) : 3556–60. http://dx.doi.org/10.1142/s0217979209062967.

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Magnetic properties of multiferroic materials consisting of ferroelectric phase and ferrite phase have been investigated. Typical magnetic hysteresis loops of prepared multiferroic materials have been observed. The coercivity increases with the increase of ferroelectric phase. However, the saturation magnetization of multiferroic materials linearly decreases with the increase of ferroelectric phase. On increasing the content of ferroelectric phase, the initial permeability of multiferroic materials decreases and the peak of the quality factor tends to shift toward higher frequency. The Curie temperature of prepared multiferroic materials shifts toward higher temperature with the increase of ferroelectric phase. The microstructures of prepared multiferroic materials also have been studied.

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Uršič, Hana, Matej Šadl, Uroš Prah et Val Fišinger. « Magnetic Force Microscopy of Multiferroic Bulk Ceramic Oxides ». Crystals 13, n^o 5 (19 mai 2023) : 838. http://dx.doi.org/10.3390/cryst13050838.

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Bulk multiferroic ceramics have been extensively studied due to their great potential for magneto-electric coupling applications such as low-power and multifunctional nano-electronic devices. In most of these studies the macroscopic magnetic performance was investigated, while the magnetic response on the micro- and nano-scale was not examined in detail. Local magnetic phenomena can be studied using magnetic force microscopy (MFM), a technique derived from atomic force microscopy. MFM measures the magnetic force between the magnetised tip and the magnetic sample. It is one of the most used methods to characterise the structure of ferromagnetic domains, because the sample preparation is simple, non-destructive and provides a relatively high-resolution image. In this review paper we focus on the MFM analyses of bulk multiferroic ceramics. The core of the article is divided into four sections: the introduction, the preparation of samples prior to MFM examination, the reviews of MFM analyses performed on bulk multiferroic ceramics with and without external magnetic fields, and finally the conclusions and an outlook for the future.

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Gareeva, Zukhra, Nikolai Shulga, Rurik Doroshenko et Anatoly Zvezdin. « Electric field control of magnetic states in ferromagnetic–multiferroic nanostructures ». Physical Chemistry Chemical Physics 25, n^o 33 (2023) : 22380–87. http://dx.doi.org/10.1039/d3cp02913a.

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Multiferroic oxides are considered as key elements of energy-consuming devices for scalable logic and information storage technologies. A model of magnetization reversal processes in a nanoscale exchange-coupled ferromagnetic–multiferroic film in an electric field has been developed.

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Xu, Dingshi, Fan Zhang, Ben Niu, Jun Du, Di Wu, Qi Li, Mingxiang Xu et Qingyu Xu. « Magnetic properties of multiferroic Pb5Fe3F19 ». Journal of Magnetism and Magnetic Materials 541 (janvier 2022) : 168540. http://dx.doi.org/10.1016/j.jmmm.2021.168540.

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Blinc, R., P. Cevc, A. Potočnik, B. Žemva, E. Goreshnik, D. Hanžel, A. Gregorovič et al. « Magnetic properties of multiferroic K3Cr2Fe3F15 ». Journal of Applied Physics 107, n^o 4 (15 février 2010) : 043511. http://dx.doi.org/10.1063/1.3309205.

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Cho, Jae-Hyeon, et Wook Jo. « Progress in the Development of Single-Phase Magnetoelectric Multiferroic Oxides ». Ceramist 24, n^o 3 (30 septembre 2021) : 228–47. http://dx.doi.org/10.31613/ceramist.2021.24.3.03.

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Magnetoelectric (ME) multiferroics manifesting the coexistence and the coupling of ferromagnetic and ferroelectric order are appealing widespread interest owing to their fascinating physical behaviors and possible novel applications. In this review, we highlight the progress in single-phase ME multiferroic oxides research in terms of the classification depending on the physical origins of ferroic properties and the corresponding examples for each case, i.e., material by material, along with their ME multiferroic properties including saturation magnetization, spontaneous polarization, (anti)ferromagnetic/ferroelectric transition temperature, and ME coefficient. The magnetoelectrically-active applications of high expectancy are presented by citing the representative examples such as magnetoelectric random-access-memory and multiferroic photovoltaics. Furthermore, we discuss how the development of ME multiferroic oxides should proceed by considering the current research status in terms of developed materials and designed applications. We believe that this short review will provide a basic introduction for the researchers new to this field.

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Kim, Sung-Baek, Bok-Yeon Kum, Chul-Sung Kim, Sung-Yong An, N. Hur, S. Park, S. W. Cheong, Kwang-Hyun Jang et J. G. Park. « Magnetic Properties of Multiferroic h-HoMnO3 ». Journal of the Korean Magnetics Society 15, n^o 2 (1 avril 2005) : 113–17. http://dx.doi.org/10.4283/jkms.2005.15.2.113.

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Zhou, Shuang, Chuanjun Dai, Qingyu Xu et Jun Du. « The magnetic properties of multiferroic BaCoF4 ». AIP Advances 7, n^o 5 (mai 2017) : 055822. http://dx.doi.org/10.1063/1.4976582.

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Yu, Yinghong, Wei Mi, Qi Li, Jun Du et Qingyu Xu. « The magnetic properties of multiferroic Sr3Fe2F12 ». Journal of Magnetism and Magnetic Materials 502 (mai 2020) : 166516. http://dx.doi.org/10.1016/j.jmmm.2020.166516.

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