Electronic structures of compensated magnetism in double perovskites A ₂CrRu(Os)O₆ (A = Si, Ge, Sn, and Pb) from ab initio calculations

We investigated possible candidates for a compensated half-metal (CHM) with a double perovskite structure A₂CrRu(Os)O₆ (A = Si, Ge, Sn, and Pb). Electronic structures and magnetic properties were analyzed using the accurate full-potential linear augmented plane wave method within the generalized gradient approximation (GGA). The compensated magnetism can be divided into half-metallic antiferromagnets (HM-AF) and antiferromagnetic insulator (AF-Is) based on their zero magnetic moments. A₂CrRuO ₆ (A = Si, Ge, Sn, and Pb) is a potential candidate for HM-AF, and Sn₂CrOsO₆ and Pb₂CrOsO₆ can be classified as AF-Is. The HM-AF and AF-Is states are both attributed to the superexchange and generalized double exchange mechanism. When the GGA + U calculation is taken into account, all A₂CrRu(Os)O₆ (A = Si, Ge, Sn, and Pb) states become unconventional AF-Is because the two AF state-coupled ions consisted of two different elements and the two spin-resolved densities of states were no longer the same. Further experimental confirmation will be done for the possible CHM of A₂CrRuO₆ (A = Si, Ge, Sn, and Pb), Sn₂CrOsO₆, and Pb₂CrOsO ₆.