Journal articles: 'Giant Ferroelectric Polarization'

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Chen, Zibin, Fei Li, Qianwei Huang, Fei Liu, Feifei Wang, Simon P. Ringer, Haosu Luo, Shujun Zhang, Long-Qing Chen, and Xiaozhou Liao. "Giant tuning of ferroelectricity in single crystals by thickness engineering." Science Advances 6, no. 42 (October 2020): eabc7156. http://dx.doi.org/10.1126/sciadv.abc7156.

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Thickness effect and mechanical tuning behavior such as strain engineering in thin-film ferroelectrics have been extensively studied and widely used to tailor the ferroelectric properties. However, this is never the case in freestanding single crystals, and conclusions from thin films cannot be duplicated because of the differences in the nature and boundary conditions of the thin-film and freestanding single-crystal ferroelectrics. Here, using in situ biasing transmission electron microscopy, we studied the thickness-dependent domain switching behavior and predicted the trend of ferroelectricity in nanoscale materials induced by surface strain. We discovered that sample thickness plays a critical role in tailoring the domain switching behavior and ferroelectric properties of single-crystal ferroelectrics, arising from the huge surface strain and the resulting surface reconstruction. Our results provide important insights in tuning polarization/domain of single-crystal ferroelectric via sample thickness engineering.

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Kimura, Tsuyoshi. "Current Progress of Research on Magnetically-induced Ferroelectrics." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C6. http://dx.doi.org/10.1107/s2053273314099938.

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Among several different types of magnetoelectric multiferroics, "magnetically-induced ferroelectrics" in which ferroelectricity is induced by complex spin orders, such as spiral orders, exhibit giant direct magnetoelectric effects, i.e., remarkable changes in electric polarization in response to a magnetic field. Not a few spin-driven ferroelectrics showing the magnetoelectric effects have been found in the past decade.[1] However, their induced ferroelectric polarization is much smaller than that in conventional ferroelectrics and mostly develops only at temperatures much lower than room temperature. Thus, the quest for spin-driven ferroelectrics with room temperature operation and/or robust ferroelectric polarization is still a major challenge in magnetoelectric multiferroics research. In this presentation, I will begin with introducing the background of research on magnetically-induced ferroelectrics, and present the following current progress. Recently, some hexaferrites have been found to show direct magnetoelectric effects at room temperature and relatively low magnetic fields.[2] Furthermore these hexferrites show inverse magnetoelectric effects, that is, induction of magnetization by applying electric fields, at room temperature. The results represented an important step toward practical applications using the magnetoelectric effect in spin-driven ferroelectrics. This presentation introduces magnetism and magnetoelectricity of several types of hexaferrites which show magnetoelectric effect at temperatures above room temperature. In addition, I will also introduce our recent work on magnetoelectric perovskite manganites with large magnetically-induced ferroelectric polarization which is comparable to that in conventional ferroelectrics. This work has been done in collaboration with T. Aoyam, K. Haruki, K. Okumura, A. Miyake, K. Shimizu, and S. Hirose.

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Xie, Lin, Linze Li, Colin A. Heikes, Yi Zhang, Zijian Hong, Peng Gao, Christopher T. Nelson, et al. "Giant Ferroelectric Polarization in Ultrathin Ferroelectrics via Boundary-Condition Engineering." Advanced Materials 29, no. 30 (June 6, 2017): 1701475. http://dx.doi.org/10.1002/adma.201701475.

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Wei, Lijing, Changliang Li, Jianxin Guo, Li Guan, Yinglong Wang, and Baoting Liu. "Giant optical absorption and ferroelectric polarization of BiCoO2S perovskite oxysulfide by first principles prediction." Physical Chemistry Chemical Physics 22, no. 20 (2020): 11382–91. http://dx.doi.org/10.1039/d0cp00057d.

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Zhou, Zhangyang, Zhipeng Gao, Zhengwei Xiong, Gaomin Liu, Ting Zheng, Yuanjie Shi, Mingzhu Xiao, et al. "Giant power density from BiFeO₃-based ferroelectric ceramics by shock compression." Applied Physics Letters 121, no. 11 (September 12, 2022): 113903. http://dx.doi.org/10.1063/5.0102102.

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Ferroelectric pulsed-power sources with rapid response time and high output energy are widely applied in the defense industry and mining areas. As the core materials, ferroelectric materials with large remnant polarization and high electrical breakdown field should generate high power under compression. Currently, lead zirconate titanate 95/5 ferroelectric ceramics dominated in this area. Due to environmental damage and limited output power of lead-based materials, lead-free ferroelectrics are highly desirable. Here, the electrical response of 0.9BiFeO3-0.1BaTiO3 (BFO-BT) ferroelectric ceramics under shock-wave compression was reported, and a record-high power density of 4.21 × 108 W/kg was obtained, which was much higher than any existing lead-based ceramics and other available energy storage materials. By in situ high-pressure neutron diffraction, the mechanism of shock-induced depolarization of the BFO-BT ceramics was attributed to pressure-induced structural transformation, and the excellent performance was further elaborated by analyzing magnetic structure parameters under high pressures. This work provides a high-performance alternative to lead-based ferroelectrics and guidance for the further development of new materials.

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Borkar, Hitesh, Vaibhav Rao, M. Tomar, Vinay Gupta, J. F. Scott, and Ashok Kumar. "Giant enhancement in ferroelectric polarization under illumination." Materials Today Communications 14 (March 2018): 116–23. http://dx.doi.org/10.1016/j.mtcomm.2017.12.004.

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Shimizu, Takao, Hiroshi Funakubo, and Naoki Ohashi. "(Invited, Digital Presentation) Materials Aspects of New Ferroelectrics with Simple Crystal Structure." ECS Meeting Abstracts MA2022-02, no. 15 (October 9, 2022): 804. http://dx.doi.org/10.1149/ma2022-0215804mtgabs.

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Ferroelectric materials are defined as the materials, of which spontaneous polarization can be switched by an external electric field. Their crystal structural symmetry makes them exhibit a variety of electric properties, such as piezoelectricity, pyroelectricity, and ferroelectricity. Because of their characteristics, they are expected to be adapted for various applications, including sensors, actuators, and non-volatile memories. Over the past decades, perovskite type ferroelectric materials have occupied the central position in both fundamental studies and applications of ferroelectric materials. On the other hand, there are a few studies on ferroelectrics with other crystal structures. This regime is now changing since HfO2-based new ferroelectric materials have been discovered. The HfO2-based dielectric materials are employed as high-k insulators of the metal-oxide-semiconductor field-effect-transistors instead of the conventional SiOx gate dielectrics, suggesting the high compatibility with semiconductor technologies. Thus, discovering ferroelectricity in HfO2-based materials strongly encourages us to develop highly integrated ferroelectric devices that are difficult to fabricate with traditional perovskite-type ferroelectrics. Amid increasing interest in ferroelectric materials, ferroelectricity is demonstrated on another new (Al, Sc)N, which has a wurtzite structure. Both fluorite structure, the parent structure of HfO2-based ferroelectrics, and wurtzite structure are simple compounds, having only a single anion and cation sites in the crystal structure. This feature contrasts the complex crystal structure of conventional perovskite structure. This presentation will give a brief outline of these new ferroelectric materials and introduce our recent studies from the viewpoint of crystal chemistry. It is well-known that HfO2 undergoes successive phase transitions from monoclinic to tetragonal and tetragonal to cubic phases. However, these phases cannot show ferroelectricity because of their inversion center in the crystal structure. It is widely accepted that the ferroelectricity in HfO2-based materials originates from the metastable orthorhombic structure. This orthorhombic structure was confirmed by the convergence electron diffraction and scanning transmission electron microscopy. Among the HfO2-based materials, HfO2- ZrO2 materials are most extensively studied. However, the thickness that can exhibit ferroelectricity in these materials is limited to less than 50 nm because of their strong preference for the monoclinic structure. In order to investigate structural features of the HfO2-based materials, materials are demanded that have ferroelectricity over the wide thickness range. The Y-doped HfO2 meets the requirement, allowing us to grow the ferroelectric film over 1 μm in thickness. Furthermore, we demonstrated ferroelectricity in epitaxial films using this composition. A recent report on ferroelectricity in bulk single-crystal also employed the Y-doped HfO2 system. The ferroelectricity in the wurtzite structure has been discussed for a long time. Moriwake et al. put forward giant spontaneous polarization in wurtzite materials by calculation based on density functional theory. The proposed mechanism of polarization reversal is accompanied by the change in the outermost surface, namely a cation surface to an anion surface and vice versa. Such large polarization was demonstrated in (Al1-x Scx)N films by Fitchtner et al. They also confirmed the change in the surface by performing chemical etching. In addition to (Al1-x Scx)N films, the ferroelectricity has been confirmed in (Al1-x B x )N, (Ga1-x Sc x )N, and (Zn1-x Mg x )O. For the wurtzite structure, we can consider the virtual paraelectric BN phase, in which both anions and cations are located in the same plane. As the paraelectric phase is deemed an intermediate state during polarization reversal, easy polarization reversal is expected as the u-parameter of the wurtzite structure approaches 0.5. It is considered that the u parameter is closely related to the axial ratio of the c- and a-axes. In fact, the reduction of coercive field and remanent polarization is ascertained experimentally. The “simple compound” ferroelectrics have attracted much attention due to their unique features, e.g., outstanding compatibility to semiconductor technologies in HfO2-based materials and giant remanent polarization in wurtzite materials. However, quite a large coercive field compared to conventional ferroelectrics reduces the reliability of the devices, particularly endurance properties. Further studies and developments to unveil microstructures under and after applying a strong electric field will lead to the next application of these ferroelectrics.

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Kumar, Ajay, Dalip Saini, and Dipankar Mandal. "3D printed ferroelectret with giant piezoelectric coefficient." Applied Physics Letters 120, no. 18 (May 2, 2022): 182901. http://dx.doi.org/10.1063/5.0091808.

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A ferroelectret cellular structure of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] is fabricated by a 3D printing technique that exhibits a giant piezoelectric coefficient of 1200 pC/N, which is 40 times higher than its commonly known film counterpart. It attributes that the bi-polar charge separation in cellular voids upon the corona discharge behaves as macroscopic dipoles. An increase in the surface potential and dielectric constant (from 10 to 20 at 1 kHz) also attributes to charged voids. Furthermore, the deviation of ferroelectric behavior, for instance, the continuous increasing trend in dielectric constant and remanent polarization as a function of temperature attributes to ferroelectret behavior of a 3D printed P(VDF-TrFE) specimen. The mechanical energy harvester (MEH) made with this ferroelectret structure shows prompt response with [Formula: see text]4 W/m2 of the power density. Furthermore, the benefit of the giant piezoelectric coefficient of the MEH is used to demonstrate self-powered tactile mapping.

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Wang, Zhihong, Xi Xiang Zhang, Xianbin Wang, Weisheng Yue, Jingqi Li, Jianmin Miao, and Weiguang Zhu. "Giant Flexoelectric Polarization in a Micromachined Ferroelectric Diaphragm." Advanced Functional Materials 23, no. 1 (August 14, 2012): 124–32. http://dx.doi.org/10.1002/adfm.201200839.

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Rouquette, Jerome, Manuel Hinterstein, Julien Haines, Michael Knapp, Julia Glaum, Jurgen Eckert, Hartmud Fuess, and Hichem Dammak. "Probing the Giant Piezoelectric response of ferroelectric perovskites." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C150. http://dx.doi.org/10.1107/s2053273314098490.

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By analogy with ferromagnetism and the hysteresis of the magnetic moment with a magnetic field, materials that exhibit a macroscopic spontaneous polarization Ps, which can be reversed under electric field E were defined as ferroelectrics. Ps, the directional order parameter can give rise to different polar structural phase transitions and finally disappear as a function of temperature T and/or hydrostatic pressure P in a transformation from a non-centrosymmetric to a centrosymmetric space group. The physical properties of ferroelectric materials are the basis of many technological applications based on their hysteretic properties (Ps / E in ferroelectric random access memories) or based on their coupled properties (η (mechanical strain)/ E in piezoelectric applications). In order to understand the origin and the mechanisms associated with the ferroelectric properties, "in-situ" structural studies as a function of E, T and P have to be performed. In addition ferroelectric materials exhibit based on their directional properties (Ps) a particular domain configuration which makes the structural understanding of these compounds much more complex. Different scales should be taken into account: from the atomic scale (individual polar displacements) to the macroscopic scale (macroscopic piezoelectric effect) and finally the mesoscopic scale in between, which is governed by the domain wall motion. High piezoelectric/ferroelectric properties in lead perovskite materials (PZT, PMN, PZN) are structurally linked to strong disorder which can be characterized by the presence of diffuse scattering in diffraction experiments and by nanosized domains. Here we will present "in-situ" characterization in lead perovskite materials as a function of the applied electric field based on X-ray and neutron diffraction and EXAFS techniques. A brief overview of the challenges to solve in future studies as a function of pressure and temperature will also be discussed.

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Yun, Kwi Young, Dan Ricinschi, Takeshi Kanashima, Minoru Noda, and Masanori Okuyama. "Giant Ferroelectric Polarization Beyond 150 µC/cm2in BiFeO3Thin Film." Japanese Journal of Applied Physics 43, No. 5A (April 16, 2004): L647—L648. http://dx.doi.org/10.1143/jjap.43.l647.

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Han, Ding-Chong, Zhi-Xiang Gong, Ning Song, Yu-Hui Tan, Yu-Kong Li, Yun-Zhi Tang, Peng-Kang Du, and Hao Zhang. "Ferroelectric properties, narrow band gap and ultra-large reversible entropy change in a novel nonlinear ionic chromium(vi) compound." Chemical Communications 57, no. 85 (2021): 11225–28. http://dx.doi.org/10.1039/d1cc04751e.

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A novel nonlinear chromium(vi) compound, [(CH3CH2)3N(CH2Cl)][CrO3Cl], undergoes a high-temperature phase transition with a moderate ferroelectric polarization of 0.48 μC cm−2, a remarkable CD signal, a giant entropy change and a narrow band gap of 2.22 eV.

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Manley, Michael E., Douglas L. Abernathy, Raffi Sahul, Daniel E. Parshall, Jeffrey W. Lynn, Andrew D. Christianson, Paul J. Stonaha, Eliot D. Specht, and John D. Budai. "Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations." Science Advances 2, no. 9 (September 2016): e1501814. http://dx.doi.org/10.1126/sciadv.1501814.

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Relaxor-based ferroelectrics are prized for their giant electromechanical coupling and have revolutionized sensor and ultrasound applications. A long-standing challenge for piezoelectric materials has been to understand how these ultrahigh electromechanical responses occur when the polar atomic displacements underlying the response are partially broken into polar nanoregions (PNRs) in relaxor-based ferroelectrics. Given the complex inhomogeneous nanostructure of these materials, it has generally been assumed that this enhanced response must involve complicated interactions. By using neutron scattering measurements of lattice dynamics and local structure, we show that the vibrational modes of the PNRs enable giant coupling by softening the underlying macrodomain polarization rotations in relaxor-based ferroelectric PMN-xPT {(1 − x)[Pb(Mg1/3Nb2/3)O3] – xPbTiO3} (x = 30%). The mechanism involves the collective motion of the PNRs with transverse acoustic phonons and results in two hybrid modes, one softer and one stiffer than the bare acoustic phonon. The softer mode is the origin of macroscopic shear softening. Furthermore, a PNR mode and a component of the local structure align in an electric field; this further enhances shear softening, revealing a way to tune the ultrahigh piezoelectric response by engineering elastic shear softening.

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Boni, Georgia A., Lucian D. Filip, Cristian Radu, Cristina Chirila, Iuliana Pasuk, Mihaela Botea, Ioana Pintilie, and Lucian Pintilie. "Indirect Evaluation of the Electrocaloric Effect in PbZrTiO3 (20/80)-Based Epitaxial Thin Film Structures." Electronic Materials 3, no. 4 (November 1, 2022): 344–56. http://dx.doi.org/10.3390/electronicmat3040028.

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Electrocaloric effect is the adiabatic temperature change in a dielectric material when an electric field is applied or removed, and it can be considered as an alternative refrigeration method. Materials with ferroelectric order exhibit large temperature variations in the vicinity of a phase transition, while antiferroelectrics and relaxors may exhibit a negative electrocaloric effect. In this study, the temperature variation in polarization was investigated for epitaxial ferroelectric thin film structures based on PbZrTiO3 materials in simple or complex multilayered structures. We propose the intriguing possibility of a giant negative electrocaloric effect (ΔT = −3.7 K at room temperature and ΔT = −5.5 K at 370 K) in a simple epitaxial Pb(ZrTi)O3 capacitor. Furthermore, it was shown that abnormal temperature variation in polarization is dependent on the non-FE component introduced in a multilayered structure. No significant variation in polarization with temperature was obtained for PZT/STON multilayered structures around room temperature. However, for PZT/BST or PZT/Nb2O5 multilayers, an abnormal temperature variation in polarization was revealed, which was similar to a simple PZT layer. The giant and negative ∆T values were attributed to internal fields and defects formed due to the large depolarization fields when the high polarization of the FE component was not fully compensated either by the electrodes or by the interface with an insulator layer. The presented results make Pb(ZrTi)O3-based structures promising for cooling applications operating near room temperature.

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Kobayashi, Tomo, Yuji Noguchi, and Masaru Miyayama. "Giant Polarization Properties of Ba-Based Bismuth Layer-Structured Ferroelectrics." Key Engineering Materials 301 (January 2006): 3–6. http://dx.doi.org/10.4028/www.scientific.net/kem.301.3.

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Intergrowth-structured Bi4Ti3O12-BaBi4Ti4O15 (BiT-BBTi) single crystals were grown by a self-flux method, and the crystal structure and polarization properties were investigated. Transmission electron microscope observations and X-ray diffraction analysis presented direct evidence of the intergrowth structure composed of the alternate stacking of BiT and BBTi layers. The BiT-BBTi crystals showed a giant spontaneous polarization (Ps) along the a axis of 52 μC/cm2, which was larger than those of the crystals of BiT (46 μC/cm2) and BBTi (16 μC/cm2). The large Ps of the BiT-BBTi crystals is suggested to originate from the ferroelectric displacements of the Bi of Bi2O2 layers as well as from the Bi substitution for Ba induced by compositional deviation. It was found that the polarization properties of the BiT-BBTi crystals depend strongly on the composition.

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Gu, Zongquan, Mohammad A. Islam, and Jonathan E. Spanier. "Giant enhancement in the ferroelectric field effect using a polarization gradient." Applied Physics Letters 107, no. 16 (October 19, 2015): 162901. http://dx.doi.org/10.1063/1.4933095.

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Zhang, Sirui, Yinlian Zhu, Yunlong Tang, Ying Liu, Shuang Li, Mengjiao Han, Jinyuan Ma, et al. "Giant Polarization Sustainability in Ultrathin Ferroelectric Films Stabilized by Charge Transfer." Advanced Materials 29, no. 46 (October 25, 2017): 1703543. http://dx.doi.org/10.1002/adma.201703543.

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Ponomarev, B. K., and A. Zhukov. "Magnetic and Magnetoelectric Properties of Rare Earth Molybdates." Physics Research International 2012 (May 9, 2012): 1–22. http://dx.doi.org/10.1155/2012/276348.

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We present results on ferroelectric, magnetic, magneto-optical properties and magnetoelectric effect of rare earth molybdates (gadolinium molybdate, GMO, and terbium molybdate, TMO, and samarium molybdate, SMO), belonging to a new type of ferroelectrics predicted by Levanyuk and Sannikov. While cooling the tetragonal β-phase becomes unstable with respect to two degenerate modes of lattice vibrations. The β-β′ transition is induced by this instability. The spontaneous polarization appears as a by-product of the lattice transformation. The electric order in TMO is of antiferroelectric type. Ferroelectric and ferroelastic GMO and TMO at room temperature are paramagnets. At low temperatures GMO and TMO are antiferromagnetic with the Neel temperatures TN=0.3 K (GMO) and TN=0.45 K (TMO). TMO shows the spontaneous destruction at 40 kOe magnetic field. Temperature and field dependences of the magnetization in TMO are well described by the magnetism theory of singlets at 4.2 K ≤ T ≤ 30 K. The magnetoelectric effect in SMO, GMO and TMO, the anisotropy of magnetoelectric effect in TMO at T = (1.8–4.2) K, the Zeeman effect in TMO, the inversion of the electric polarization induced by the laser beam are discussed. The correlation between the magnetic moment of rare earth ion and the magnetoelectric effect value is predicted. The giant fluctuations of the acoustic resonance peak intensity near the Curie point are observed.

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Chen, Xin, Vladimir Shvartsman, Doru C. Lupascu, and Q. M. Zhang. "Comment on “Giant pyroelectric energy harvesting and a negative electrocaloric effect in multilayered nanostructures” by G. Vats, A. Kumar, N. Ortega, C. R. Bowen and R. S. Katiyar, Energy Environ. Sci., 2016, 9, 1335." Energy & Environmental Science 14, no. 3 (2021): 1612–14. http://dx.doi.org/10.1039/d0ee02548h.

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In the ferroelectric phase, the change of polarization with temperature from partially switched polarization hysteresis loops has no relation with the electrocaloric effect (ECE) and hence cannot be used in Maxwell relation to deducing ECE.

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Delimova, L. A., E. V. Guschina, V. S. Yuferev, I. V. Grekhov, N. V. Zaiceva, N. V. Sharenkova, D. S. Seregin, K. A. Vorotilov, and A. S. Sigov. "Giant Self-Polarization in FeRAM Element Based on Sol-Gel PZT Films." MRS Proceedings 1729 (2015): 87–92. http://dx.doi.org/10.1557/opl.2015.214.

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ABSTRACTIntegrated ferroelectric capacitors Pt/PZT/Pt/Ti/SiO2/Si with sol-gel deposited PZT films are studied. The (111) textured polycrystalline films are shown to have nonconductive PZT grain boundaries. The short-circuited photocurrents measured under illumination of the films by light with the quantum energy of 2.7 eV indicate the polarization inside the film directed from the top to the bottom electrode. Using the modified method of depolarization hysteresis loops, we found a non-switchable part of polarization which was measured to be -16 μC/cm2 and directed from the top to the bottom electrode. We consider this result to be a giant self-polarization and explain it in terms of flexoelectricity caused by lattice mismatch between the PZT and bottom Pt layers. The strain gradient across the PZT film thickness is estimated from the in-plane lattice constants measured in Pt and PZT films to be ∼103cm-1, which can produce the downward flexoelectric polarization of ∼14 μC/cm2, coinciding well with the measured one. Nonsymmetrical depolarization loops are found in the films when the polarization switching itself becomes more difficult under the negative or positive driving voltage. We show experimentally how depolarization with compensating bias or film illumination can affect the film polarization switching.

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Wang, F., B. Li, Y. Ou, L. F. Liu, C. Z. Peng, Z. S. Wang, and W. Wang. "Giant room temperature elastocaloric effect of PbTiO3 ferroelectric materials with 90° domain structure." RSC Advances 6, no. 74 (2016): 70557–62. http://dx.doi.org/10.1039/c6ra13030e.

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The elastocaloric effect in PbTiO₃ with 90° domain structure under the applied stress field at room temperature has been studied. A negative ΔTσ of −7.2 K can be obtained by controlled polarization switching under the applied stress fields.

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Blinov, L. M., V. V. Lazarev, S. P. Palto, and S. G. Yudin. "Giant quadratic electro-optical effect during polarization switching in ultrathin ferroelectric polymer films." Journal of Experimental and Theoretical Physics 114, no. 4 (April 2012): 691–97. http://dx.doi.org/10.1134/s1063776112030016.

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Sakai, Hideaki, Koji Ikeura, Mohammad Saeed Bahramy, Naoki Ogawa, Daisuke Hashizume, Jun Fujioka, Yoshinori Tokura, and Shintaro Ishiwata. "Critical enhancement of thermopower in a chemically tuned polar semimetal MoTe2." Science Advances 2, no. 11 (November 2016): e1601378. http://dx.doi.org/10.1126/sciadv.1601378.

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Ferroelectrics with spontaneous electric polarization play an essential role in today’s device engineering, such as capacitors and memories. Their physical properties are further enriched by suppressing the long-range polar order, as exemplified by quantum paraelectrics with giant piezoelectric and dielectric responses at low temperatures. Likewise in metals, a polar lattice distortion has been theoretically predicted to give rise to various unusual physical properties. However, to date, a “ferroelectric”-like transition in metals has seldom been controlled, and hence, its possible impacts on transport phenomena remain unexplored. We report the discovery of anomalous enhancement of thermopower near the critical region between the polar and nonpolar metallic phases in 1T′-Mo1−xNbxTe2with a chemically tunable polar transition. It is unveiled from the first-principles calculations and magnetotransport measurements that charge transport with a strongly energy-dependent scattering rate critically evolves toward the boundary to the nonpolar phase, resulting in large cryogenic thermopower. Such a significant influence of the structural instability on transport phenomena might arise from the fluctuating or heterogeneous polar metallic states, which would pave a novel route to improving thermoelectric efficiency.

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Kumar, Ashok, and Hitesh Borkar. "Flexoelectricity in Bulk and Nanoscale Polar and Non-Polar Dielectrics." Solid State Phenomena 232 (June 2015): 213–33. http://dx.doi.org/10.4028/www.scientific.net/ssp.232.213.

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Piezoelectricity (PE) is defined as the polarization under homogeneous application of stress on polar/non-centrosymmetry/no-inversion symmetry dielectrics, whereas it has been commonly accepted that flexoelectricity (FLX) is the induced polarization due to strain gradient in any polar/nonpolar dielectrics, the latter effect is universal and can be generated in any materials under inhomogeneous stress. Flexoelectricity is inversely proportional to the size of materials and devices which further suggests that giant FLX effects may develop in nanoscale materials. Flexoelectricity represents the polarization due to strain gradient and have significant effects on the functional properties of nanoscale materials, epitaxial thin films, one-dimensional structure with various shape and size, liquid crystals, polymers, nanobio-hybrid materials, etc. Till late sixties, very few works on flexoelectricity have been reported due to very weak magnitude compared to piezoelectricity. Advancement in nanoscale materials and device fabrication process and highly sophisticated electronics with detection of data with high signal to noise ratio lead the scientists/researchers to get several orders of higher flexoelectric coefficients compared to the proposed theoretical limits. Recently, giant FLX have been observed in nanoscale materials and their magnitudes are six to seven orders larger than the theoretical limits. In this review article, we describe the basic mechanism of flexoelectricity, brief history of discovery, theoretical modeling, experimental procedures, and results reported by several authors for bulk and nanoscale ferroelectric and dielectric materials.

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Fan, Zhen, Juanxiu Xiao, Huajun Liu, Ping Yang, Qingqing Ke, Wei Ji, Kui Yao, Khuong P. Ong, Kaiyang Zeng, and John Wang. "Stable Ferroelectric Perovskite Structure with Giant Axial Ratio and Polarization in Epitaxial BiFe0.6Ga0.4O3 Thin Films." ACS Applied Materials & Interfaces 7, no. 4 (January 21, 2015): 2648–53. http://dx.doi.org/10.1021/am509016w.

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Pan, Tianze, Ji Zhang, Dongxiao Che, Zhengyu Wang, Jiajia Wang, Jing Wang, and Yaojin Wang. "Improved capacitive energy storage in sodium niobate-based relaxor antiferroelectric ceramics." Applied Physics Letters 122, no. 7 (February 13, 2023): 072902. http://dx.doi.org/10.1063/5.0134282.

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Ceramic-based dielectric capacitors have become an attractive issue due to their wide applications in current pulsed-/high-power electronic devices. Antiferroelectric ceramics generally exhibit ultrahigh energy density owing to their giant polarization activated by antiferroelectric–ferroelectric phase transition under a high electric field but suffer from large hysteresis, meanwhile giving rise to low efficiency. Herein, by introducing perovskite compound Sr(Fe0.5Ta0.5)O3 into an antiferroelectric NaNbO3 matrix, a stabilized antiferroelectric phase and an improved relaxor behavior are observed. That is, relaxor antiferroelectric ceramics are constructed. Accordingly, a double polarization–electric field ( P–E) loop becomes slimmer with increasing incorporation of dopants, leading to an ultrahigh recoverable energy density of 11.5 J/cm3, an energy storage efficiency of 86.2%, outstanding frequency/cycling/thermal reliability, and charge–discharge properties in 0.90NaNbO3-0.10Sr(Fe0.5Ta0.5)O3 ceramics. This work reveals that inducing the relaxor behavior in antiferroelectric materials is an effective route to improve their capacitive energy storage.

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Chen, Peng, and Bang-Gui Liu. "Giant ferroelectric polarization and electric reversal of strong spontaneous magnetization in multiferroic Bi 2 FeMoO 6." Journal of Magnetism and Magnetic Materials 441 (November 2017): 497–502. http://dx.doi.org/10.1016/j.jmmm.2017.06.019.

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Cai, Changlong, Deqiang Zhang, Weiguo Liu, Jun Wang, Shun Zhou, Yongming Su, Xueping Sun, and Dabin Lin. "Synthesis, Giant Dielectric, and Pyroelectric Response of [001]-Oriented Pr3+ Doped Pb(Mg1/3Nb2/3)O3-PbTiO3 Ferroelectric Nano-Films Grown on Si Substrates." Materials 11, no. 12 (November 28, 2018): 2392. http://dx.doi.org/10.3390/ma11122392.

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The [001]-oriented Pr3+ doped Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (Pr-PMN-PT) thin films with a composition near the morphotropic phase boundary (MPB) were synthesized by a sol–gel method. The crystal structure was characterized using X-ray diffraction. It was found that a single perovskite phase was achieved in Pr-PMN-PT thin films annealed at 650 °C for 3 min. The dielectric constant (εr) value was 2400 in 2.5% Pr-PMN-PT thin films at room temperature, 110% higher than that of pure PMN-PT samples. Through 2.5% Pr3+ doping, remanent polarization (Pr) and coercive field (Ec) values increased from 11.5 μC/cm2 and 35 kV/cm to 17.3 μC/cm2 and 63.5 kV/cm, respectively, in PMN-PT thin films. The leakage current densities of pure and 2.5% Pr-PMN-PT thin films were on the order of 1.24 × 10−4 A/cm2 and 5.8 × 10−5 A/cm2, respectively, at 100 kV/cm. A high pyroelectric coefficient (py) with a value of 167 μC/m2K was obtained in 2.5% Pr-PMN-PT thin films on Si substrate, which makes this material suitable for application in infrared detectors.

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29

Matsuda, Hirofumi, Sachiko Ito, and Takashi Iijima. "Giant Ferroelectric Polarization in Polar-Axis-Oriented Bi_4-xPr_xTi₃O₁₂ Polycrystalline Thin Films." Key Engineering Materials 269 (August 2004): 45–48. http://dx.doi.org/10.4028/www.scientific.net/kem.269.45.

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30

Höfling, Marion, Xiandong Zhou, Lukas M. Riemer, Enrico Bruder, Binzhi Liu, Lin Zhou, Pedro B. Groszewicz, et al. "Control of polarization in bulk ferroelectrics by mechanical dislocation imprint." Science 372, no. 6545 (May 27, 2021): 961–64. http://dx.doi.org/10.1126/science.abe3810.

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Defects are essential to engineering the properties of functional materials ranging from semiconductors and superconductors to ferroics. Whereas point defects have been widely exploited, dislocations are commonly viewed as problematic for functional materials and not as a microstructural tool. We developed a method for mechanically imprinting dislocation networks that favorably skew the domain structure in bulk ferroelectrics and thereby tame the large switching polarization and make it available for functional harvesting. The resulting microstructure yields a strong mechanical restoring force to revert electric field–induced domain wall displacement on the macroscopic level and high pinning force on the local level. This induces a giant increase of the dielectric and electromechanical response at intermediate electric fields in barium titanate [electric field–dependent permittivity (ε33) ≈ 5800 and large-signal piezoelectric coefficient (d33*) ≈ 1890 picometers/volt]. Dislocation-based anisotropy delivers a different suite of tools with which to tailor functional materials.

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31

Niu, Ruirui, Zhuoxian Li, Xiangyan Han, Zhuangzhuang Qu, Dongdong Ding, Zhiyu Wang, Qianling Liu, et al. "Giant ferroelectric polarization in a bilayer graphene heterostructure." Nature Communications 13, no. 1 (October 21, 2022). http://dx.doi.org/10.1038/s41467-022-34104-z.

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AbstractAt the interface of van der Waals heterostructures, the crystal symmetry and the electronic structure can be reconstructed, giving rise to physical properties superior to or absent in parent materials. Here by studying a Bernal bilayer graphene moiré superlattice encapsulated by 30°-twisted boron nitride flakes, we report an unprecedented ferroelectric polarization with the areal charge density up to 1013 cm−2, which is far beyond the capacity of a moiré band. The translated polarization ~5 pC m−1 is among the highest interfacial ferroelectrics engineered by artificially stacking van der Waals crystals. The gate-specific ferroelectricity and co-occurring anomalous screening are further visualized via Landau levels, and remain robust for Fermi surfaces outside moiré bands, confirming their independence on correlated electrons. We also find that the gate-specific resistance hysteresis loops could be turned off by the other gate, providing an additional control knob. Furthermore, the ferroelectric switching can be applied to intrinsic properties such as topological valley current. Overall, the gate-specific ferroelectricity with strongly enhanced charge polarization may encourage more explorations to optimize and enrich this novel class of ferroelectricity, and promote device applications for ferroelectric switching of various quantum phenomena.

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32

Qi, He, Tengfei Hu, Shiqing Deng, Hui Liu, Zhengqian Fu, and Jun Chen. "Giant dynamic electromechanical response via field driven pseudo-ergodicity in nonergodic relaxors." Nature Communications 14, no. 1 (April 27, 2023). http://dx.doi.org/10.1038/s41467-023-38006-6.

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AbstractEnhanced electromechanical response can commonly be found during the crossover from normal to relaxor ferroelectric state, making relaxors to be potential candidates for actuators. In this work, (Pb0.917La0.083)(Zr0.65Ti0.35)0.97925O3 ceramic was taken as a case study, which shows a critical nonergodic state with both double-like P-E loop and irreversible relaxor-normal ferroelectric phase after poling at room temperature. The low-hysteresis linear-like S-P2 loop, in-situ synchrotron X-ray diffraction and transmission electron microscope results suggest that the nonpolar relaxor state acts as a bridge during polarization reorientation process, accompanying which lattice strain contributes to 61.8% of the total strain. In other words, the transformation from normal ferroelectric to nonergodic relaxor state could be triggered by electric field through polarization contraction, which could change to be spontaneously with slightly increasing temperature in the nonergodic relaxor zone. Therefore, pseudo-ergodicity in nonergodic relaxors (i.e. reversible nonergodic-normal ferroelectric phase transition) driven by periodic electric field should be the main mechanism for obtaining large electrostrain close to the nonergodic-ergodic relaxor boundary. This work provides new insights into polarization reorientation process in relaxor ferroelectrics, especially phase instability in nonergodic relaxor zone approaching to freezing temperature.

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Lee, N., C. Vecchini, Y. J. Choi, L. C. Chapon, A. Bombardi, P. G. Radaelli, and S.-W. Cheong. "Giant Tunability of Ferroelectric Polarization inGdMn2O5." Physical Review Letters 110, no. 13 (March 26, 2013). http://dx.doi.org/10.1103/physrevlett.110.137203.

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34

Huang, Cheng, Xiaojun Wang, and Jinbo Zhao. "Large electrocaloric effects induced by multidomain-to-monodomain transition in ferroelectrics with electrical inclusions." Frontiers in Energy Research 11 (August 28, 2023). http://dx.doi.org/10.3389/fenrg.2023.1257567.

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The electrocaloric effect (ECE) depends on the sudden change of the polarization field during ferroelectric phase transition near the Curie temperature. Similarly, giant ECE can be found enormously during the domain structure transition from multidomain to monodomain process in ferroelectrics. To reveal the mechanism with the effects of the electric inclusions, the ECE of PbTiO3 (PTO) ferroelectric solids under electric loads is investigated by phase-field simulation. The giant ECEs of ferroelectric materials containing three kinds of electric inclusions, namely, air, silicone oil, and water, are discussed in detail under applied electric fields. The results suggest that an unusual ultrahigh negative ECE (−9.30 K) and a large EC strength (∆T/∆E=0.237 KmMV−1 are achieved near room temperature (about 50°C) in ferroelectrics containing water inclusion. The results indicate that electric inclusions generate high electrostatic energy under electric loads to break through the energy barrier and play an importation role in the ECE. In summary, the works may provide a better way to obtain the giant ECE and large EC strength close to room temperature by effectively regulating the dielectric constant of the electric inclusion and the increment of the applied electric field.

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35

Shen, Shiying, Haoqiang Ai, Yandong Ma, Haoyun Bai, Xuejian Du, Feifei Li, and Hui Pan. "In-plane ferroelectric monolayer TlNbX4O and its application in bulk photovoltaic effect." Applied Physics Letters 123, no. 5 (July 31, 2023). http://dx.doi.org/10.1063/5.0156495.

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A bulk photovoltaic effect (BPVE) in materials without inversion symmetry attracts increasing interest for high-efficiency solar cells beyond the p–n junction paradigm. Herein, we report the photovoltaic effect in an experimentally feasible TlNbX4O monolayer (TlNbX4O-ML, X = Cl, Br, I) with a large ferroelectric polarization. Using first-principles calculations, we demonstrate that TlNbX4O-MLs are ferroelectric semiconductors with moderate switching barriers and higher spontaneous polarizations. Furthermore, we observe fairly giant shift current with the values of 109.6 μA/V2 for TlNbCl4O, 60 μA/V2 for TlNbBr4O, and 56.1 μA/V2 for TlNbI4O. These results unveil distinct features of the BPVE and the potential application of two-dimensional ferroelectric materials for next-generation photovoltaic devices.

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36

Tsukada, Shinya, Yasuhiro Fujii, Akari Kanagawa, Yukikuni Akishige, and Kenji Ohwada. "Polarization behavior in a compositionally graded relaxor–ferroelectric crystal visualized by angle-resolved polarized Raman mapping." Communications Physics 6, no. 1 (May 18, 2023). http://dx.doi.org/10.1038/s42005-023-01219-8.

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AbstractExplaining the properties and functions of materials in terms of their atomic arrangements and inhomogeneous structures is a fundamental challenge for the development of ferroelectric oxides. Dielectric response, a fundamental property of matter, can be explained by long-wavelength polar lattice vibrations and dipole relaxations capable of responding to electrical bias; therefore spectroscopic methods, such as Raman spectroscopy, can be used to investigate its origin. Herein, we used angle-resolved polarized Raman mapping to investigate how phase boundaries and giant dielectric responses are related in a relaxor-Pb(Mg1/3Nb2/3)O3–ferroelectric-PbTiO3 (PMN-xPT) solid-solution system using a compositionally graded crystal, with gradual changes in polarization direction visualized by Raman mapping. The variation of the width of quasielastic light scattering with position reveals the following: The huge dielectric response observed in PMN-xPT is ascribable to the slowing down of a relaxation related to mesoscopic ferroelectric domains near the phase boundary, which is characteristic of relaxor–ferroelectric solid-solution systems and differentiates them from other ferroelectrics.

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37

Lee, Jun Hee, and Randy S. Fishman. "Giant Spin-Driven Ferroelectric Polarization inBiFeO3at Room Temperature." Physical Review Letters 115, no. 20 (November 11, 2015). http://dx.doi.org/10.1103/physrevlett.115.207203.

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38

Yin, Jie, Xiaoming Shi, Hong Tao, Zhi Tan, Xiang Lv, Xiangdong Ding, Jun Sun, et al. "Deciphering the atomic-scale structural origin for large dynamic electromechanical response in lead-free Bi0.5Na0.5TiO3-based relaxor ferroelectrics." Nature Communications 13, no. 1 (October 25, 2022). http://dx.doi.org/10.1038/s41467-022-34062-6.

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AbstractDespite the extraordinary electromechanical properties of relaxor ferroelectrics, correlating their properties to underlying atomic-scale structures remains a decisive challenge for these “mess” systems. Here, taking the lead-free relaxor ferroelectric Bi0.5Na0.5TiO3-based system as an example, we decipher the atomic-scale structure and its relationship to the polar structure evolution and large dynamic electromechanical response, using the direct atomic-scale point-by-point correlation analysis. With judicious chemical modification, we demonstrate the increased defect concentration is the main driving force for deviating polarizations with high-angle walls, leading to the increased random field. Meanwhile, the main driving force for deviating polarizations with low-angle walls changes from the anti-phase oxygen octahedral tilting to the multidirectional A-O displacement, leading to the decreased anisotropy field. Benefiting from the competitive and synergetic equilibrium of anisotropic field versus random field, the facilitated polarization rotation and extension versus facilitated domain switching are identified to be responsible for the giant electromechanical response. These observations lay a foundation for understanding the “composition-structure-property” relationships in relaxor ferroelectric systems, guiding the design of functional materials for electromechanical applications.

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39

Liu, Zifang, Pengfei Hou, Lizhong Sun, Evgeny Y. Tsymbal, Jie Jiang, and Qiong Yang. "In-plane ferroelectric tunnel junctions based on 2D α-In2Se3/semiconductor heterostructures." npj Computational Materials 9, no. 1 (January 13, 2023). http://dx.doi.org/10.1038/s41524-022-00953-x.

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AbstractFerroelectric tunnel junctions (FTJs) have great potential for application in high-density non-volatile memories. Recently, α-In2Se3 was found to exhibit robust in-plane and out-of-plane ferroelectric polarizations at a monolayer thickness, which is ideal to serve as a ferroelectric component in miniaturized electronic devices. In this work, we design two-dimensional van der Waals heterostructures composed of an α-In2Se3 ferroelectric and a hexagonal IV–VI semiconductor and propose an in-plane FTJ based on these heterostructures. Our first-principles calculations show that the electronic band structure of the designed heterostructures can be switched between insulating and metallic states by ferroelectric polarization. We demonstrate that the in-plane FTJ exhibits two distinct transport regimes, tunneling and metallic, for OFF and ON states, respectively, leading to a giant tunneling electroresistance effect with the OFF/ON resistance ratio exceeding 1 × 104. Our results provide a promising approach for the high-density ferroelectric memory based on the 2D ferroelectric/semiconductor heterostructures.

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40

Zhang, J. X., Q. He, M. Trassin, W. Luo, D. Yi, M. D. Rossell, P. Yu, et al. "Microscopic Origin of the Giant Ferroelectric Polarization in Tetragonal-likeBiFeO3." Physical Review Letters 107, no. 14 (September 29, 2011). http://dx.doi.org/10.1103/physrevlett.107.147602.

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41

Aoyama, T., K. Yamauchi, A. Iyama, S. Picozzi, K. Shimizu, and T. Kimura. "Giant spin-driven ferroelectric polarization in TbMnO3 under high pressure." Nature Communications 5, no. 1 (September 12, 2014). http://dx.doi.org/10.1038/ncomms5927.

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42

Liu, Xitao, Zhenyue Wu, Tong Guan, Haidong Jiang, Peiqing Long, Xiaoqi Li, Chengmin Ji, Shuang Chen, Zhihua Sun, and Junhua Luo. "Giant room temperature electrocaloric effect in a layered hybrid perovskite ferroelectric: [(CH3)2CHCH2NH3]2PbCl4." Nature Communications 12, no. 1 (September 24, 2021). http://dx.doi.org/10.1038/s41467-021-25644-x.

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AbstractElectrocaloric effect driven by electric fields displays great potential in realizing highly efficient solid-state refrigeration. Nevertheless, most known electrocaloric materials exhibit relatively poor cooling performance near room temperature, which hinders their further applications. The emerging family of hybrid perovskite ferroelectrics, which exhibits superior structural diversity, large heat exchange and broad property tenability, offers an ideal platform. Herein, we report an exceptionally large electrocaloric effect near room temperature in a designed hybrid perovskite ferroelectric [(CH3)2CHCH2NH3]2PbCl4, which exhibits a sharp first-order phase transition at 302 K, superior spontaneous polarization (>4.8 μC/cm2) and relatively small coercive field (<15 kV/cm). Strikingly, a large isothermal entropy change ΔS of 25.64 J/kg/K and adiabatic temperature change ΔT of 11.06 K under a small electric field ΔE of 29.7 kV/cm at room temperature are achieved, with giant electrocaloric strengths of isothermal ΔS/ΔE of 0.86 J·cm/kg/K/kV and adiabatic ΔT/ΔE of 370 mK·cm/kV, which is larger than those of traditional ferroelectrics. This work presents a general approach to the design of hybrid perovskite ferroelectrics, as well as provides a family of candidate materials with potentially prominent electrocaloric performance for room temperature solid-state refrigeration.

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Gupta, Reema, Monika Tomar, Vinay Gupta, Yuan Zhou, Anuj Chopra, Shashank Priya, A. S. Bhalla, and R. Guo. "Giant Magnetoelectric Effect in PZT Thin Film Deposited on Nickel." Energy Harvesting and Systems 3, no. 2 (January 1, 2016). http://dx.doi.org/10.1515/ehs-2015-0010.

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AbstractThe magnetoelectric (ME) effect has been investigated in lead zirconate titanate (PZT) thin film deposited on nickel foil using chemical solution deposition (CSD) technique. The synthesized PZT thin films are found to possess perovskite structure without presence of any intermediate layer. PZT thin film deposited on nickel foil exhibits a good ferroelectric property with a high remnant polarization of about 86 µC/cm

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44

Kang, Lili, Peng Jiang, Hua Hao, Yanhong Zhou, Xiaohong Zheng, Lei Zhang, and Zhi Zeng. "Giant tunneling electroresistance in two-dimensional ferroelectric tunnel junctions with out-of-plane ferroelectric polarization." Physical Review B 101, no. 1 (January 14, 2020). http://dx.doi.org/10.1103/physrevb.101.014105.

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45

Gao, Zhaomeng, Weifeng Zhang, Qilan Zhong, Yonghui Zheng, Shuxian Lv, Qiqiao Wu, Yanling Song, et al. "Giant electroresistance in hafnia-based ferroelectric tunnel junctions via enhanced polarization." Device, June 2023, 100004. http://dx.doi.org/10.1016/j.device.2023.100004.

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46

Kremer, Geoffroy, Julian Maklar, Laurent Nicolaï, Christopher W. Nicholson, Changming Yue, Caio Silva, Philipp Werner, et al. "Field-induced ultrafast modulation of Rashba coupling at room temperature in ferroelectric α-GeTe(111)." Nature Communications 13, no. 1 (October 27, 2022). http://dx.doi.org/10.1038/s41467-022-33978-3.

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AbstractRashba materials have appeared as an ideal playground for spin-to-charge conversion in prototype spintronics devices. Among them, α-GeTe(111) is a non-centrosymmetric ferroelectric semiconductor for which a strong spin-orbit interaction gives rise to giant Rashba coupling. Its room temperature ferroelectricity was recently demonstrated as a route towards a new type of highly energy-efficient non-volatile memory device based on switchable polarization. Currently based on the application of an electric field, the writing and reading processes could be outperformed by the use of femtosecond light pulses requiring exploration of the possible control of ferroelectricity on this timescale. Here, we probe the room temperature transient dynamics of the electronic band structure of α-GeTe(111) using time and angle-resolved photoemission spectroscopy. Our experiments reveal an ultrafast modulation of the Rashba coupling mediated on the fs timescale by a surface photovoltage, namely an increase corresponding to a 13% enhancement of the lattice distortion. This opens the route for the control of the ferroelectric polarization in α-GeTe(111) and ferroelectric semiconducting materials in quantum heterostructures.

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47

Grishin, A., S. Khartsev, P. Johnsson, and A. Maneikis. "Epitaxial Giant Magnetoresistive/Ferroelectric La0.7Ca0.3MnO.3/PbZr0.52Ti0.48O3 Thin Film Heterostructures." MRS Proceedings 541 (1998). http://dx.doi.org/10.1557/proc-541-673.

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AbstractRecently, doped rare-earth manganates exhibiting colossal magnetoresistivity have been proposed to be used as the semiconductor channel material for a Ferrolectric Field Effect Transistor. Although the feasibility of epitaxial magnetoresistive/ferroelectric heterostructures have been demonstrated, the leakage in the ferrolectric layer and the strain induced degradation of the magnetoresitive layer remain a principal problem. We present results on fabrication and characterization of epitaxial giant magnetoresistive/ferrolectric La0.7Ca0.3MnO3(LCMO)/PbZr0.52TiO.48O3(PZT) heterostructures. The films have been prepared in situ by a KrF pulsed laser deposition technique on single crystal LaAlO3 substrates from stoichiometric LCMO and PZT targets. The main processing parameters have been optimized to preserve the existence of giant magnetoresitivity in the LCMO films after deposition of the top ferrolectric layer. A high degree of c-axis orientation and a strong in-plane texture coherent with the substrate both in template LCMO and PZT layers, high dielectric permittivity of 1800, remanent polarization of 0.2 C/m2 and a magnetoresistivity of 28% at H=0.5 T indicate excellent characteristics of coexisting magnetoresistive and ferroelectric properties.

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Urru, Andrea, Francesco Ricci, Alessio Filippetti, Jorge Íñiguez, and Vincenzo Fiorentini. "A three-order-parameter bistable magnetoelectric multiferroic metal." Nature Communications 11, no. 1 (October 1, 2020). http://dx.doi.org/10.1038/s41467-020-18664-6.

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Abstract Using first-principles calculations we predict that the layered-perovskite metal Bi5Mn5O17 is a ferromagnet, ferroelectric, and ferrotoroid which may realize the long sought-after goal of a room-temperature ferromagnetic single-phase multiferroic with large, strongly coupled, primary-order polarization and magnetization. Bi5Mn5O17 has two nearly energy-degenerate ground states with mutually orthogonal vector order parameters (polarization, magnetization, ferrotoroidicity), which can be rotated globally by switching between ground states. Giant cross-coupling magnetoelectric and magnetotoroidic effects, as well as optical non-reciprocity, are thus expected. Importantly, Bi5Mn5O17 should be thermodynamically stable in O-rich growth conditions, and hence experimentally accessible.

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49

Resta, R., S. Massidda, M. Posternak, and A. Baldereschi. "Polarization, Dynamical Charge, and Bonding in Partly Covalent Polar Insulators." MRS Proceedings 408 (1995). http://dx.doi.org/10.1557/proc-408-9.

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AbstractWe have investigated the macroscopic polarization and dynamical charges of some crystalline dielectrics presenting a mixed ionic/covalent character. First principles investigations have been done within the Hartree-Fock, LDA, and model GW approaches. All calculations have been performed on the same footing, using the all-electron FLAPW scheme. Apparently similar oxides have strikingly different behaviors: some (like the ferroelectric perovskites) have giant dynamical charges, while others (like ZnO) are quite normal and display dynamical charges close to the nominal static ones. We find the rationale for such differences.

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Sannigrahi, J., S. Bhowal, S. Giri, S. Majumdar, and I. Dasgupta. "Exchange-striction induced giant ferroelectric polarization in copper-based multiferroic materialα−Cu2V2O7." Physical Review B 91, no. 22 (June 23, 2015). http://dx.doi.org/10.1103/physrevb.91.220407.

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Journal articles on the topic 'Giant Ferroelectric Polarization'

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