Electronic structures of the ferrimagnetic double-perovskites Sr 2 XReO 6 (X=Cr, Mn, Fe, Ni) with the modified Becke-Johnson potential

We investigate the electronic structures and magnetic properties of the ferrimagnetic double-perovskites Sr 2 XReO 6 (X=Cr, Mn, Fe, Ni) by using Tran and Blaha’s modified Becke and Johnson exchange potential. The calculated results show that Sr 2 XReO 6 (X=Cr, Fe) are half-metals, and Sr 2 XReO 6 (X=Mn, Ni) are insulators, which is in accordance with the experimental results. By using the ionic picture, we explain the trend in the density of states and total magnetic moment with X changing from Cr to Ni. We find that the insulating property is associated with X 2 + , while the metallic character is associated with X 3 + . The Re t 2g splitting in the minority channel leads to insulativity of Sr 2 XReO 6 (X=Mn, Ni), and the Re t 2g splitting of Sr 2 MnReO 6 is caused by lattice distortion, while Sr 2 NiReO 6 ’s splitting is due to the heavier atomic mass of Ni. When spin-orbit coupling is included, the spin polarization of Sr 2 XReO 6 (X=Cr, Fe) drifts off 100%, and the related gaps of Sr 2 XReO 6 (X=Mn, Ni) become narrow. The spin-orbit coupling results in a significant increase in the total magnetic moment due to an unquenched Re orbital moment. Our calculated energy band structures show that Sr 2 MnReO 6 is a spin gapless semiconductor, which can realize fully polarized spin-down electrons and spin-up holes. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2015