First-principles study of structural and electronic properties of multiferroic oxide Mn3TeO6 under high pressure

Mn3TeO6 (MTO) has been experimentally found to adopt a P2(1)/n structure under high pressure, which exhibits a significantly smaller band gap compared to the atmospheric R (3) over bar phase. In this study, we systematically investigate the magnetism, structural phase transition, and electronic properties of MTO under high pressure through first-principles calculations. Both R (3) over bar and P2(1)/n phases of MTO are antiferromagnetic at zero temperature. The R (3) over bar phase transforms to the P2(1)/n phase at 7.58 GPa, accompanied by a considerable volume collapse of about 6.47%. Employing the accurate method that combines DFT+U and GW, the calculated band gap of R (3) over bar phase at zero pressure is very close to the experimental values, while that of the P2(1)/n phase is significantly overestimated. The main reason for this difference is that the experimental study incorrectly used the Kubelka-Munk plot for the indirect band gap to obtain the band gap of the P2(1)/n phase instead of the Kubelka-Munk plot for the direct band gap. Furthermore, our study reveals that the transition from the R (3) over bar phase to the P2(1)/n phase is accompanied by a slight reduction in the band gap.