Density functional study of structural, electronic and magnetic properties of new half-metallic ferromagnetic double perovskite Sr₂MnVO₆

In this paper, a new half-metallic (HM) double perovskite compound is predicted with the simultaneous presence of ferromagnetism and polar distortion. The structural, electronic and magnetic properties of Sr₂MnVO₆ (SMVO) are calculated by density functional theory (DFT) with both generalized gradient approximation (GGA) and GGA  +  U approaches, where U is the on-site Coulomb interaction parameter. Different orderings of B (B′) cationic sites in A₂BB′O₆ double perovskite structure are evaluated, including rocksalt, columnar and layered arrangements for cubic, monoclinic and tetragonal crystal structures. It is found that the most stable ordering is obtained when B and B′ are placed in a layered type ordering for a tetragonal crystal structure with I4/m space group, which is confirmed by phonon calculations. The B-site ordering of the Mn³⁺ and V⁵⁺ ions in a layered configuration leads to ferromagnetically coupled magnetic moments of 4.17 µ _B at Mn site and 0.23 µ _B at V site. Finally, SMVO is found to be a half-metallic ferromagnetic (HM-FM) compound with a band gap of 0.65 eV in a spin down channel with off-centered displacement of V atoms in the octahedral cage (second order Jahn -Teller effect) which can cause ferroelectricity. Therefore, SMVO is predicted to be a polar HM material and a promising candidate for multiferroic property with potential application in spintronics. (paper)