High-temperature multiferroicity and strong magnetocrystalline anisotropy in 3d-5d double perovskites

TL;DR

This study predicts that certain 3d-5d double perovskites with Bi ions can exhibit high-temperature multiferroicity and strong magnetocrystalline anisotropy, enabling electric control of magnetization at room temperature.

Contribution

First-principles calculations reveal potential for room-temperature multiferroicity and large anisotropy in Bi-based 3d-5d double perovskites, guiding experimental synthesis.

Findings

Bi$_2$NiReO$_6$ and Bi$_2$MnReO$_6$ are insulating with net magnetization above room temperature.

Constrained lattice vectors induce ferroelectricity with large polarization.

Large uniaxial magnetocrystalline anisotropy with easy axis along polarization.

Abstract

Using density functional calculations we explore the properties of as-yet-unsynthesized $3d - 5d$ ordered double perovskites ($A_2BB'$O$_6$) with highly polarizable Bi$^{3+}$ ions on the $A$ site. We find that the Bi$_2$NiReO$_6$ and Bi$_2$MnReO$_6$ compounds are insulating and exhibit a robust net magnetization that persists above room temperature. When the in-plane lattice vectors of the pseudocubic unit cell are constrained to be orthogonal (for example, by coherent heteroepitaxy), the ground states are ferroelectric with large polarization and a very large uniaxial magnetocrystalline anisotropy with easy axis along the ferroelectric polarization direction. Our results suggest a route to multiferroism and electrically controlled magnetization orientation at room temperature.