Pseudo-half-metalicity in the double perovskite Sr$_2$CrReO$_6$ from density-functional calculations

The electronic structure of the spintronic material Sr 2 CrReO 6 is studied by means of full-potential linear muffin-tin orbital method. Scalar relativistic calculations predict Sr 2 CrReO 6 to be half-metallic with a magnetic moment of 1 µ B . When spin-orbit coupling is included, the half-metallic gap closes into a pseudo-gap, and an unquenched rhenium orbital moment appears, resulting in a significant increase of the total magnetic moment to 1.28 µ B . This moment is significantly larger than the experimental moment of 0.9 µ B . A possible explanation of this discrepancy is that the anti-site disorder in Sr 2 CrReO 6 is significantly larger than hitherto assumed.