Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session A53: Multiferroics, Magnetoelectrics, Spin-Electric Coupling, and Ferroelectrics - 1Focus Live
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Sponsoring Units: DMP DCOMP GMAG Chair: Turan Birol, University of Minnesota |
Monday, March 15, 2021 8:00AM - 8:12AM Live |
A53.00001: Ultrafast and non-linear optical studies of multiferroic BaTiO3-BiFeO3 and heterostructures based on ferroelectric Pb 0.52 Zr 0.48 TiO 3 Rathsara Herath Mudiyanselage, Brenden A Magill, Jade Holleman, Stephen A McGill, Han-Byul Kang, Min Gyu Kang, Shashank Priya, Christopher J Stanton, Giti Khodaparast Multiferroic (0.285) BaTiO3- (0.725) BiFeO3 (BTO-BFO) and Pb 0.52 Zr 0.48 TiO 3 (PZT) heterostructures are promising candidates for photonics and spintronics. Our BTO-BFO structures exhibit enhanced coupling between electric, magnetic, optical, and structural orders parameters. Furthermore, our PZT structures display ferroelectricity as well as enhanced switching response of their electrical polarization. In our work, we focused on probing ultrafast dynamics and nonlinear light-matter interactions in these structures. We have probed second harmonic generation, transient birefringence, and magneto-optical Kerr effects. In addition, in BTO-BFO heterostructures, we have generated and investigated coherent acoustic phonons. Our studies are important to gain a fundamental understanding of the dynamical processes in these newly developed structures. |
Monday, March 15, 2021 8:12AM - 8:24AM Live |
A53.00002: Ferroelectric switching in the Aurivillius phase oxide SrBi2Ta2O9 from first principles Nabaraj Pokhrel, Elizabeth A Nowadnick The Aurivillius phases are a family of layered perovskites with general formula Bi2mAn−m BnO3(n+m) , in which Bi2O2layers alternate with perovskite-like blocks. Theoretical and first-principles studies during the past decade have revealed that the coupling of the polarization with non-polar lattice distortions such as octahedral rotations plays a significant role in the structural phase transitions and ground state ferroelectric structure of the Aurivillius phase oxide SrBi2Ta2O9. However, the implication of this coupling on the ferroelectric switching mechanism, which requires that one of the octahedral rotations must reverse along with the polarization, has received minimal attention. Here, we use density functional theory calculations and group theoretic analysis to explore symmetry-distinct intrinsic ferroelectric switching pathways of SrBi2Ta2O9. By tracking the evolution of the non-polar lattice distortions as well as the polarization along each switching path, we uncover how the couplings between multiple lattice distortions facilitate the switching process. This work provides new understanding of the role of non-linear lattice couplings in the ferroelectric switching mechanisms of the structurally complex family of Aurivillius phase oxides. |
Monday, March 15, 2021 8:24AM - 8:36AM Live |
A53.00003: Giant Linear Magnetoelectric Effect at the Morphotropic Phase Boundary of Epitaxial Sr0.5Ba0.5MnO3 films Temuujin Bayaraa, Yurong Yang, Meng Ye, Laurent Bellaiche The search for magnetoelectric multiferroics possessing a strong coupling between their ferroelectric and magnetic properties has attracted great interest, both for technological and fundamental purposes. The understanding of the underlying mechanism behind magnetoelectric coupling is a crucial line of research. |
Monday, March 15, 2021 8:36AM - 8:48AM Live |
A53.00004: Pressure-induced metal-insulator transition in oxygen-deficient ferroelectrics Chengliang Xia, Yue Chen, Hanghui Chen Pressure and oxygen vacancies are usually considered as deleterious for ferroelectric materials because both tend to reduce their polarization. Extending our previous work (Phys. Rev. Materials 3, 054405 (2019)), we perform first-principles calculations to show that in oxygen-deficient LiNbO3−δ, pressure induces a novel metal-insulator transition around 8-9 GPa. Strong polar displacements are robust in both metallic and insulating LiNbO3−δ. The transition arises from the change of an oxygen vacancy defect state. Pressure increases the polar displacements of LiNbO3−δ, which reduces the band width of the defect state and eventually turns it into an in-gap state. In the insulating phase, the in-gap state is further pushed away from the conduction band edge under pressure, which increases the fundamental gap. Our work shows that for LiNbO3-type strong ferroelectrics, combining oxygen vacancies and pressure can lead to new phenomena and potential functions, in contrast to the harmful effects occurring to perovskite ferroelectric oxides such as BaTiO3. |
Monday, March 15, 2021 8:48AM - 9:00AM Live |
A53.00005: Optical and structural properties of type-II multiferroic candidates RbFe(AMO4)2 (A = Mo, Se, S) Rachel Owen, Elizabeth Drueke, Charlotte Albunio, Austin R Kaczmarek, Wencan Jin, Dimuthu Obeysekera, Sang-Wook Cheong, Junjie Yang, Steven Thomas Cundiff, Liuyan Zhao Motivated by the search for type-II multiferroics, we present an optical study of a complex oxide family of type-II multiferroic candidates: RbFe(MoO4)2, RbFe(SeO4)2, and RbFe(SO4)2. We employ rotational-anisotropy second harmonic generation spectroscopy (RA SHG) to address discrepancies in reported space groups. Additionally, we present temperature-dependent linear optical characterizations near the band edge of this family of materials using ultraviolet-visible (UV-VIS) absorption spectroscopy. Included is experimental evidence of the band gap energy and band gap transition type for this family. We also show unreported sub-band gap absorption that reveals prominent optical transitions. Finally, we discuss the impact of these optical transitions as well as the implications of the point symmetries in each material at various temperatures. |
Monday, March 15, 2021 9:00AM - 9:12AM Live |
A53.00006: Magnetocapacitance Effect and Magnetoelectric Coupling in Type-II Multiferroic HoFeWO6 Moein Adnani Takantapeh, Melissa Gooch, Liangzi Deng, Stefano Agrestini, Javier Herrero-Martín, Hung-Cheng Wu, Chung-Kai Chang, Taha Salavati-fard, Narayan Poudel, José Luis García-Muñoz, Samira Daneshmandi, Zheng Wu, Lars Grabow, Yen-Chung Lai, Hung-Duen Yang, Eric J Pellegrin, Paul C. W. Chu We have studied the magnetocapacitance (MC) effect and magnetoelectric (ME) coupling in HoFeWO6, a type-II multiferroic with an onset of electric polarization and an antiferromagnetic (AFM) ordering at the Neel temperature (TN) of 17.8 K. With a polar structure at room temperature, our X-ray diffraction measurements did not show any structural phase transition across TN, consistent with our density functional theory calculations. Our X-ray absorption spectroscopy and X-ray magnetic circular dichroism revealed the valence state of 3+ for Fe and Ho cations and AFM ordering of Fe3+ spins in a non-collinear fashion with spins arranged 90 degrees with respect to each other. The compound exhibits MC effect with double-hysteresis loop behavior that is in direct correspondence with the magnetization. The observed MC effect and the change in polarization by the magnetic field, as well as their direct correspondence with magnetization, further support the strong ME coupling in this compound. |
Monday, March 15, 2021 9:12AM - 9:48AM Live |
A53.00007: Unconventional ferroelectricity from competing states in perovskites Invited Speaker: Michele Kotiuga According to conventional wisdom, ferroelectricity in ABO3 perovskite oxides is driven by a soft polar mode, giving rise to insulating polar states that can be switched by an applied electric field. In recent years, in part motivated by the search for multiferroics, there has been great interest in the design and discovery of ferroelectrics with alternative mechanisms. In this talk, I will explore this avenue further, presenting two situations in which competing states play a pivotal role. |
Monday, March 15, 2021 9:48AM - 10:00AM Live |
A53.00008: Unique and unusual properties of layered ferrielectric CuInP2S6 – II. Experimental Sabine Neumayer, Lei Tao, John Brehm, Andrew O'Hara, Mengwei Si, Pai-Ying Liao, Peide (Peter) Ye, Michael A McGuire, Michael Susner, Sokrates T Pantelides, Petro Maksymovych, Nina Balke The multifunctionality and van der Waals (vdW) layered structure of CuInP2S6 provides opportunities to achieve ultrathin electromechanical devices. The orientation and magnitude of the polarization in CuInP2S6 is determined by the position of Cu ions, which following theoretical predictions of 4 polarization states can either reside within layers or displace into the vdW gap (theoretical abstract by L. Tao).1 These four stable uniaxial polarization states can be identified using a combination of density functional theory and scanning probe microscopy. Cu is also the most mobile ion, which leads to a unique interplay of ionic and ferroelectric properties that allows polarization alignment against an electric field.2 This type of switching is underpinned by Cu motion across the vdW gap activated by the electric field. Based on this phenomenon, a polarization switching regime associated with negative capacitance is accessible.3 Similar functionality is expected in other materials where polar and ionic properties manifest in the same ionic sublattice. |
Monday, March 15, 2021 10:00AM - 10:12AM Live |
A53.00009: Unique and unusual properties of layered ferrielectric CuInP2S6 - I. Theory Lei Tao, Sabine Neumayer, Andrew O'Hara, John Brehm, Petro Maksymovych, Nina Balke, Sokrates T Pantelides CuInP2S6 (CIPS) is a van der Waals layered ferrielectric with out-of-plane polarization and an ionic conductor. By combining density-functional-theory calculations and piezoelectric-force-microscopy experiments (next abstract by S. Neumayer et al.), we demonstrate that CIPS features a quadruple-well potential with four polarization states, corresponing1 to Cu atoms displacing within or just outside the CIPS layers. Under an applied voltage, the Cu atoms can go beyond the HP state and cross the vdW gaps, at which point the polarization aligns against the electric field.2 Further, because CIPS has two centrosymmetric planes, middle of layers and middle of vdW gaps, the polarization curve as a function of Cu displacements has a negative slope within the vdW gaps, signaling a regime of negative capacitance by a novel mechanism. This talk will describe the theoretical findings. It is followed by a talk (S. Neumayer et al.) on experimental validation. The unique and unusual properties of CIPS present new opportunities for novel applications. |
Monday, March 15, 2021 10:12AM - 10:24AM Live |
A53.00010: Influence of Polarization, Strain, and Doping on the Magnetoelectric Properties of LSMO/PZT Interfaces: An Ab Initio Study Krishna Acharya, Igor Vasiliev We apply ab initio methods based on density functional theory to study the influence of polarization, strain, and doping on the magnetoelectric coupling at the (0,0,1) interface between PZT (PbZr0.2Ti0.8O3) and LSMO at three different doping levels (La0.8Sr0.2MnO3, La0.67Sr0.33MnO3, and La0.5Sr0.5MnO3). The effects of strain are modeled by applying a ±1% uniaxial strain in the direction orthogonal to the LSMO/PZT interface. Our calculations show that the magnetic properties of the LSMO layer are strongly influenced by the direction of PZT polarization, doping concentration, and the applied uniaxial strain. An increase of the Sr doping level increases the energy of the ferromagnetic phase and decreases the energy of the antiferromagnetic phase of LSMO. A positive strain stabilizes the ferromagnetic configuration of LSMO, whereas a negative strain stabilizes the antiferromagnetic configuration of LSMO. The results of our study are consistent with the available experimental data. |
Monday, March 15, 2021 10:24AM - 10:36AM Live |
A53.00011: Studying the Ferroelectric Domain Memory-Dependent Evolutions in Multiferroic BTO/CFO Janus Nanofibers Exploiting a Magnetic Field Saba Arash, Bryan Chavez, Matthew Bauer, Jennifer Andrew, Thomas M Crawford, Yanwen Wu Multiferroic (MF) materials with coexisting ferroelectricity and ferromagnetism exhibit memory, a behavior that leads to the development of many novel applications. In this work to further explore this behavior, the ferroelectric domains are optically observed in BTO/CFO Janus nanofibers using magnetic polarization resolved second harmonic generation measurement technique. Analysis of the non-magnetic BTO domain changes at room temperature indicates that the ferroelectric memory can be predicted and manipulated exploiting a magnetic field. In addition, I present a physical interpretation to demonstrate these memory-dependent evolutions in MF Janus nanofibers. The realization of this memory effect in this specific geometry provides a promising route to design a new generation of nanoscale memory devices. |
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