Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session JJ01: V: Multiferroics and Ferroelectrics IFocus
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Sponsoring Units: DMP Chair: Rui Liu, University of Wisconsin-Madison Room: Virtual Room 1 |
Monday, March 20, 2023 3:00PM - 3:36PM |
JJ01.00001: Multiferroics beyond inorganics Invited Speaker: Young Sun A large number of single-phase multiferroics have been discovered in the past two decades. Most of them are inorganic materials, especially transition metal oxides. In contrast, less attention has been paid to multiferroics beyond inorganic materials. In this talk, I introduce two groups of multiferroics that are made of organic components. The first group is multiferroic metal-organic frameworks (MOFs) that exhibit direct and converse magnetoelectric (ME) effects as well as a variety of unusual physical properties. The second group is multiferroic single-molecule magnets (SMMs) that are a special class of organic magnets characterized by resonant quantum tunnelling of magnetization. When ferroelectricity is introduced into a Dy-based SMM, pronounced ME effects are achieved. The quantum tunnelling of magnetization can be directly controlled by applying a moderate electric field and the electric polarization can be modulated by applying a small magnetic field. Additionally, a resonant magnetodielectric effect is clearly observed, which enables electrical detection of quantum tunnelling of magnetization. Multiferroic SMMs not only broaden the family of multiferroics but also pave a path toward practical applications of SMMs. |
Monday, March 20, 2023 3:36PM - 3:48PM |
JJ01.00002: Direct observation of geometric and sliding ferroelectricity in an amphidynamic crystal Ning Ding Sliding ferroelectricity is a recently observed polarity existing in two-dimensional materials. However, due to the weak polarization and poor electrical insulation in these materials, existing experimental evidences are indirect and mostly based on nanoscale transport properties or piezoresponse force microscopy. We report the direct observation of sliding ferroelectricity, using a high-quality amphidynamic single crystal (15-crown-5)Cd3Cl6, which possesses a large bandgap and so allows direct measurement of polarization–electric field hysteresis. This coordination polymer is a van der Waals material, which is composed of inorganic stators and organic rotators as determined by X-ray diffraction and NMR characterization. From density functional theory calculations, we find that after freezing the rotators, an electric dipole is generated in each layer driven by the geometric mechanism, while a comparable ferroelectric polarization originates from the interlayer sliding. The net polarization of these two components can be directly measured and manipulated. Our finding provides insight into low-dimensional ferroelectrics, especially control of the synchronous dynamics of rotating molecules and sliding layers in solids. |
Monday, March 20, 2023 3:48PM - 4:00PM |
JJ01.00003: Exploring the structure of AlScN with thermal diffuse scattering from first-principles Guru Khalsa, Matthew Dykes The recent discovery of ferroelectricity in semiconducting Sc-doped AlN holds great promise for future applications in microelectromechanical devices and integrated circuit technology. Experimental studies are currently underway to determine the precise effects of Sc-doping levels on the material's crystal structure and switching dynamics. Here, we apply a complementary theoretical approach to address these issues using first-principles calculations of the all-phonon scattering intensity within the formalism of density-functional theory. In this way, we can produce diffuse scattering maps of AlScN over a wide range of reciprocal space and temperatures, to be compared with and inform experiment. |
Monday, March 20, 2023 4:00PM - 4:12PM |
JJ01.00004: Harnessing Inter-ferroelectric Phase Transformations: Path to large transduction and giant energy conversion Peter Finkel Relaxor ferroelectric single crystals with composition near a morphotropic phase boundary (MPB) are attractive for applications in actuators, transducers, and low-power sensors due to their extremely large piezoelectric response. Notoriously, this MPB can be moved through the application of stress or electric field induced rhombohedral (R) ferroelectric to orthorhombic (O) ferroelectric phase transition in [011] cut Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystal relaxor ferroelectric. The aim of this talk is twofold. First, I will present the results demonstrating how possible to achieve simultaneous electric and elastic control of ferroelectric phases in PIN-PMN-PT that can be tuned through combination of stress and applied electric field. Direct observations of this phase transition with X-ray and Raman scattering reveal the local symmetry while sweeping through the transition with a low applied electric field (0.35% for tens of millions of cycles with little fatigue. Second, I will discuss these results of the observed lack of fatigue in terms of very low energy barrier between two phases that might be explaining practically anhysteretic and simultaneous polarization switching. Details of these results on the inter-ferroelectric phase transition.and implications to further development of a wide range of devices will be presented. |
Monday, March 20, 2023 4:12PM - 4:24PM |
JJ01.00005: Electric-field-induced magnetochiral dichroism in a ferroaxial crystal NiTiO3 Takeshi Hayashida, Kenta Kimura, Tsuyoshi Kimura NiTiO3 is known as a representative ferroaxial material, which exhibits a spontaneous and uniform rotational structural distortion. Such a rotational distortion is characterized by the breaking of a mirror symmetry whose mirror plane includes the rotation axis. In contrast to chirality in which any mirror symmetry is forbidden, a mirror symmetry with the mirror plane perpendicular to the rotation axis is allowed in a ferroaxial material. In other words, chirality can be induced in a ferroaxial material by breaking the remaining mirror symmetry by applying external fields. In NiTiO3, optical activity induced by an electric field, called electrogyration, has been observed, which is regarded as the effect owing to electric field induced chirality. In this work, we focus on another effect characteristic of chiral materials, magnetochiral dichroism (MChD). MChD is asymmetry in optical absorption between two counter propagating light beams in a magnetized chiral material. In NiTiO3, electric-field-induced MChD is expected to be observed when electric and magnetic fields are simultaneously applied. We measured transmittance spectra of NiTiO3 under simultaneous applications of electric and magnetic fields along the rotation axis (the c axis). As a result, we observed finite directional dichroism whose signal is proportional to both applied electric and magnetic fields. This result is nothing less than electric-field-induced MChD in a ferroaxial material. |
Monday, March 20, 2023 4:24PM - 4:36PM |
JJ01.00006: Fe3+ optical activity in the THz due to the rare earth smaller ion size in RFeO3 (R= Er, Lu) Néstor E Massa, Karsten Holldack, Leire del Campo, Vinh Ta Phuoc, Paula Kayser, José A Alonso We report on Fe3+ induced RFeO3 (R= Er, Lu) absorptions and magnetic behavior up to 7 T measured at the THz BESSY II coherent source. The proven lattice ductility of distorted perovskites has profound implications for enabling perovskite B site crystal field (CF) symmetry forbidden Fe3+ transitions of the 6A1 multiplet. Fe3+ ground state Zeeman split is a distinctive feature of the LuFeO3 THz spectra that additionally weighs to the spin modes only picture in LaFeO3, that closer to cubic, prevents Fe3+ (CF) transitions becoming optically active. Although both compounds share the Pbnm (D2h16) space group, the Fe3+ site point group in LuFeO3 is altered by the ligand distortions due to Lu3+ smaller ionic radius in a cage with only six Lu-O nearest neighbors with non-centrosymmetric subtle deformations in Fe3+-O ligands. These Fe3+ CF Zeeman branching in LuFeO3 has a counterpart in the ErFeO3 Er3+ (4I15/2) multiplet now strongly biased due to iron - rare earth exchanges and populatin deviations. The iron absorption shows as a distinctive Boson peak in near normal FIR reflectivity. The local induced minute lattice displacements underly the possibility of assigning non-centrosymmetry that when associated to the intrinsic oxygen electronic anisotropy allows ferroelectric spontaneous polarization |
Monday, March 20, 2023 4:36PM - 4:48PM |
JJ01.00007: Finite-Bias Calculations of Perovskite Oxide Ferroelectric Tunnel Junctions using Multi-Space Density Functional Theory Kaptansinh S Rajput, Ryong Gyu Lee, Tae Hyung Kim, Hyeonwoo Yeo, Juho Lee, Yong-Hoon Kim Ferroelectric tunnel junctions (FTJs) have received considerable attention among all memory technologies as a solution to the statistical fluctuation in nanometer scales and the continued scaling-down requirement. In this work, based on the multi-space constrained-search density functional theory (MS-DFT) recently developed in our group [1-3], we study the finite-bias electronic structure and quantum transport characteristics of capacitor models composed of BaTiO3 perovskite oxides sandwiched between the metallic SrRuO3 electrodes. Based on the electric enthalpy concept, we calculate free energy profiles at different nonequilibrium bias conditions in a first-principles manner. Bias-dependent free energy plots then directly reveal the information regarding the competition between paraelectric and ferroelectric phases, polarization switching barrier height, and coercive voltage. The source of polarization switching will be analyzed by discriminating the electronic and ionic contributions and utilizing Hartree electrostatic potentials, Landauer residual dipoles, and depolarization fields. The results will be also compared with previous works obtained from equilibrium DFT calculations and their extensions. To our knowledge, our work represents the first study of nonequilibrium energetics in FTJs within the first-principles framework, demonstrating that MS-DFT is a promising tool for the future developments of energy and memory devices. |
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