O. Nganba Meetei, Onur Erten, Mohit Randeria, Nandini Trivedi, Patrick Woodward
The double perovskite Sr2CrOsO6 (SCOO) is an insulator with remarkable magnetic properties, including the highest transition temperature Tc=725 K among all perovskites with a net moment. We derive a new criterion for the Mott transition (U1 U2)^{1/2} > 2.5W using slave rotor mean field theory, where U1(2) is the ?effective Coulomb interaction on Cr(Os), incorporating Hund's coupling, and W is the bandwidth. We show that SCOO is a multi-band Mott insulator, where the large Cr U1 compensates for the small Os U2. The spin sector is described by a frustrated antiferromagnetic Heisenberg model that naturally explains the net moment as arising from canting and also the observed non-monotonic magnetization M(T). We predict characteristic magnetic structure factor peaks that can be probed by neutron scattering experiments.
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http://arxiv.org/abs/1205.1811
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