Strong coupling between a permalloy ferromagnetic contact and a helical   edge channel in a narrow HgTe quantum well
  We experimentally investigate spin-polarized electron transport between a permalloy ferromagnet and the edge of a two-dimensional electron system with band inversion, realized in a narrow, 8~nm wide HgTe quantum well. In zero magnetic field, we observe strong asymmetry of the edge potential distribution with respect to the ferromagnetic ground lead. This result indicates, that the helical edge channel, specific for the structures with band inversion even at the conductive bulk, is strongly coupled to the ferromagnetic side contact, possibly due to the effects of proximity magnetization. It allows selective and spin-sensitive contacting of helical edge states. 
A. Kononov, S.V. Egorov, Z.D. Kvon, N.N. Mikhailov, S.A. Dvoretsky,   and E.V. Deviatov
cond-mat.mes-hall