Abstract
Two CaMnBSbO6 (B = Cr and Fe) high-pressure double double perovskites are reported. Spins in CaMnCrSbO6 order below T-C = 49K into a collinear ferrimagnetic arrangement with spins in the xy plane. CaMnFeSbO6 has the same ordered magnetic structure below T-C1 = 55 K, but also shows a second magnetic transition at T-C2 = 21K where the spins reorient towards the z axis. This may reflect a greater degree of magnetic disorder for B = Fe and A-B intersite charge transfer may also be significant.