Theoretical prediction of multiferroicity in double perovskite Y$_2$NiMnO$_6$

TL;DR

This paper predicts that double perovskites of the R$_2$NiMnO$_6$ family can be multiferroic, with their magnetic and electric properties tunable via rare-earth element substitution and external electric fields, based on ab initio calculations.

Contribution

It introduces a new class of multiferroic materials within the R$_2$NiMnO$_6$ family and explains their magnetic and ferroelectric properties through theoretical modeling.

Findings

Changing R from La to Y induces a magnetic transition.

E*-type ordering breaks inversion symmetry, leading to ferroelectricity.

External electric fields can tune the magnetic transition.

Abstract

We put forward double perovskites of the R$_2$NiMnO$_6$ family (with $R$ a rare-earth atom) as a new class of multiferroics on the basis of {\it ab initio} density functional calculations. We show that changing $R$ from La to Y drives the ground-state from ferromagnetic to antiferromagnetic with $\uparrow\uparrow\downarrow\downarrow$ spin patterns. This E$^*$-type ordering breaks inversion symmetry and generates a ferroelectric polarization of few $\mu C/cm^2$. By analyzing a model Hamiltonian we understand the microscopic origin of this transition and show that an external electric field can be used to tune the transition, thus allowing electrical control of the magnetization.