Cation ordering induced semiconductor to half metal transition in La2NiCrO6

Abstract

La₂NiCrO₆, previously proposed to be a candidate of half metallic antiferromagnetism, is revisited using the first-principles calculation. Electron correlation is considered and cation ordering effects are studied by arranging Ni and Cr atoms along [111] and [001]. For the [111] case, which corresponds to an ordered double perovskite, a monoclinic structure is predicted to be the most stable. In contrast to the previous study, it is insulating from the calculation of electron structure. Attractively, the magnetic coupling of Ni and Cr is sensitive to electron correlation, i.e., it is antiferromagnetic in the GGA calculation, whereas the ferromagnetic state is favoured when electron correlation (U) is turned on. For the [001] case, it is ferromagnetic whether U is included or not. Interestingly, a semiconductor to half metal transition is expected according to the GGA + U method, and the half metallic character could be preserved under both compressive and tensile strain.