Giant electronic polarization induced by a helical spin order in SrMn₇O₁₂: First-principles calculations

¹ Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University - Nanjing 210093, China
² Department of Physics, Southeast University - Nanjing 211189, China

^(a) sdong@seu.edu.cn
^(b) liujm@nju.edu.cn

Received: 4 December 2014
Accepted: 11 December 2014

Abstract

Through first-principles density functional calculations, the magnetic ground state and electronic structure of mixed-valent manganite SrMn₇O₁₂ in the rhombohedral symmetry are investigated in detail. Our calculations show clearly that the possible magnetic ground state accommodates a particular helical spin order responsible for the insulating state in SrMn₇O₁₂. The giant ferroelectric polarization is revealed, which is almost purely from the electronic contribution rather than the ionic displacements and is closely related to the magnetism. The influence of the on-site Coulomb interaction and spin-orbit coupling on the electronic structure and multiferroicity is also discussed. The present results suggest that SrMn₇O₁₂ is a promising multiferroic candidate with desirable properties.