Ferrimagnetism and spin reorientation in the high-pressure double double perovskites <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ca</mml:mi><mml:mi>Mn</mml:mi><mml:mi>Cr</mml:mi><mml:mi>Sb</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ca</mml:mi><mml:mi>Mn</mml:mi><mml:mi>Fe</mml:mi><mml:mi>Sb</mml:mi><mml:msub><mml:mi …

Two $\mathrm{CaMn}B\mathrm{Sb}{\mathrm{O}}_{6}$ ($B=\mathrm{Cr}$ and Fe) high-pressure double perovskites are reported. Spins in $\mathrm{Ca}\mathrm{Mn}\mathrm{Cr}\mathrm{Sb}{\mathrm{O}}_{6}$ order below ${T}_{\mathrm{C}}=49\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ into a collinear ferrimagnetic arrangement with spins the $xy$ plane. $\mathrm{Ca}\mathrm{Mn}\mathrm{Fe}\mathrm{Sb}{\mathrm{O}}_{6}$ has same ordered magnetic structure ${T}_{\mathrm{C}1}=55$ K, but also shows second transition at ${T}_{\mathrm{C}2}=21\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ where reorient towards $z$ axis. This may reflect greater degree of disorder for $B=\mathrm{Fe}$ A-B intersite charge transfer be significant.