Improper ferroelectricity at antiferromagnetic domain walls of perovskite oxides

Abstract

First-principles calculations are performed on magnetic multidomain structures in the SmFeO 3 rare-earth orthoferrite compound. We focus on the magnetic symmetry breaking at (001)-oriented anti-phase domain walls, treating magnetism in the simplest (collinear) approximation without any relativistic (spin-orbit coupling) effects. We found that the number of FeO 2 layers inside the domains determines the electrical nature of the whole system: multidomains with odd mumber of layers are paraelectric, while multidomains with even number of layers possess an electric polarization aligned along b-axis and a resulting multiferroic Pmc2 1 ground state. Our ab initio data and model for ferroelectricity induced by spin order reveal that this polarization is of the improper type, and originates from an exchange striction mechanism that drives a polar displacement of the oxygen ions located at the magnetic domain walls. Additional calculations ratify that this effect is general among magnetic perovskites with an orthorhombic SmFeO 3-like structure.

Magnetic Domain-Wall Induced Electric Polarization in NdCrO3 Polycrystalline Ceramic

“…Yanez-Vilar [7] reported that a polarization may arise as a result of anti-phase AFM domain boundaries, i.e., it does not require non-collinear magnetism or spin-orbit coupling. In addition, Yang reported that an improper polarization originates from an exchange striction mechanism that drives a polar displacement of the oxygen ions located at the magnetic domain walls in SmFeO3 with an orthorhombic structure [9]. Moreover, additional calculations ratified that the mechanism was general among magnetic perovskites with an orthorhombic SmFeO3-like structure.…”

“…Until now, several mechanisms have been established for magnetically induced ferroelectricity, such as metal-ligand p-d hybridization, symmetric-exchange striction, and antisymmetric inverse Dzyaloshinskii-Moriya interaction [4][5][6]. In recent years, the polarization induced by the magnetic domain wall has been demonstrated theoretically, such as those occurring in Lu 2 CoMno 6 [7], R 2 NiMno 6 [8] and AFeO 3 (A = Lu, Y, Gd, Sm) [9,10].…”

“…In this work, we studied the magnetic, dielectric and magnetoelectric properties of a NdCrO 3 polycrystalline sample in the temperature range of 5 K-360 K. We observed interesting novel phenomena such as the dielectric anomaly at reorientation temperature (~38 K) of Cr 3+ , which could be affected by the magnetic field and may indicate an electric polarization. The magnetic field-dependent polarization could be induced by the presence of anti-phase antiferromagnetic (AFM)-type domain walls, which leads to spatial inversion symmetry breaking [9].…”

Routes to Low-Energy Magnetic Electronics

“…The electric polarization of domain walls can be the result of several microscopic mechanisms: (i) Dzyaloshinskii-Moriya-like interaction 6 due to spinorbit coupling that is enhanced in Bi-rich sample, 7 (ii) the local decompensation of the antiferroelectric structure in the domain wall, [8][9][10] (iii) the nonrelativistic interaction 11 without involving any spinorbit coupling. In the latest case, the polarization of the domain wall is chirality independent.…”

Single-phase multiferroics: new materials, phenomena, and physics

“…In addition, while multiferroicity and ME coupling are most frequently discussed as bulk effects, 2D multiferroics and domain wall multiferroicity, which are so far less addressed but definitely appealing, have been revealed recently [ 7 ]. Even more, while realization of cross-controls of multiple ferroic orders, which offers routes to entirely new device architectures and may bring a revolution in information processing and storage, has been the main stream of multiferroic research, a number of fascinating phenomena not in the main stream but sufficiently compelling, such as non-reciprocity [ 8 , 9 ], topological orders [ 10 ], and thermal Hall effects [ 11 ], have been discovered in multiferroic materials.…”