Combined asymmetry-induced and exchange-induced spin splitting in antimonide type-II quantum wells

We incorporate bulk and structure inversion asymmetries into an eight-band effective bond-orbital method to study the effects of an adjacent ferromagnetic GaMnSb layer on the transport and spin properties of high-mobility electrons in an asymmetric AlSb/GaSb/InAs/AlSb quantum well. An appreciable exchange interaction for electrons results, due to their hybridization with holes in the GaSb layer, which in turn overlap the GaMnSb. Interactions between the asymmetry and exchange effects cause these structures to have complicated spin splittings and spin orientations. When the GaMnSb magnetization points parallel to the growth axis, the spin polarization for electrons conducting in the plane can be as high as 71%. The conductivity decreases by two orders of magnitude when turning off the magnetization or rotating it toward the plane induces a transition from a gapless state to a more conventional type-II semimetal with a hybridization gap.