Prediction of Magnetoelectric behavior in Bi2MnTiO6
  We present results from ab initio calculations based on density functional theory for bismuth-based double perovskite Bi2MnTiO6. Using total energy calculation with stress and force minimization we have predicted the equilibrium crystal structure for Bi2MnTiO6 considering potential structures into the calculation. We have predicted that the ground state of Bi2MnTiO6 will be a noncentrosymmetric rhombohedral structure with space group R3c. Our spin polarized calculation for different possible collinear magnetic configurations we found that Bi2MnTiO6 will be an insulator with G-type antiferromagnetic ordering in its ground state. The coexistence of both stereochemically active Bi-6s lone pair and the Ti4+ with d0-ness which bring covalency results in the stabilization of noncentrosymmetric structure and thus ferroelectricity. Our orbital projected density of states plot shows that the Mn2+ in Bi2MnTiO6 will be at high spin state with a spin moment of 4.28 {\mu}B. Hence Bi2MnTiO6 is predicted to be a magnetoelectric material. 
Lokanath Patra and P. Ravindran
cond-mat.mtrl-sci