A route to multiferroics by non-d⁰ cation B in magnetic perovskites

Hui Wang and J. G. Che^a

Surface Physics Laboratory (National Key Laboratory), Key Laboratory of Computational Physical Sciences (MOE) and Department of Physics, Fudan University - Shanghai 200433, PRC

^a jgche@fudan.edu.cn

Received: 21 August 2011
Accepted: 9 November 2011

Abstract

Based on first-principles calculations on BaTcO₃, we explored a route to promoting ferroelectricity by non-d⁰ cation B in magnetic perovskites, leading to the co-existence of magnetic and dielectric ordering in a single phase. The ground state of the perovskite BaTcO₃ was found to be an insulator with G-type antiferromagnetic order. A tensile strain in BaTcO₃ not only inverted the lowest unoccupied states dominated from t_2g to e_g, driving the ferroelectric distortion, but also enlarged this driven force due to the induced narrower gap as its divisor. The tensile strain simultaneously weakened the repulsive force when Tc distorted to one apex of the O-octahedron in BaTcO₃. Most importantly, since the physics of our finding is not Tc specific, the route is generally applicable to other magnetic perovskites.