Spin-orbit coupling fields in hybrid ferromagnet/semiconductor heterostructures

The microscopic structure of spin-orbit fields at interfaces such as Fe/GaAs is uncovered from first principles. A symmetry based me- thod allows obtaining the spin-orbit fields — both their magnitude and orientation — for a generic Bloch state, from the electronic band structure for any in-plane magnetization orientation. It is demonstrated that the spin-orbit fields depend not only on the electric field across the interface, but also surprisingly strongly on the Fe magnetization orien- tation. The possible formation of helical interface states due to strong spin-orbit fields at nonmagnetic interfaces is also briefly discussed.