We have fabricated devices to investigate electrical spin injection from a ferromagnetic (Ga,Mn)As layer into a non-magnetic GaAs layer in the lateral transport geometry. The Esaki diode structure p⁺-(Ga,Mn)As/n⁺-GaAs is used to circumvent the problem of fast spin relaxation of holes injected from a p-type ferromagnet into GaAs. Under a reverse bias applied to such a structure spin-polarized electrons, with longer spin relaxation times than holes, tunnel from (Ga,Mn)As valence band through the depletion layer into GaAs conduction band [1]. Here we report on magnetotransport investigations of the Esaki diode in both in-plane and perpendicular external magnetic field. The sample was rotated in the in-plane field to investigate the dependence of the resulting magnetoresistance on the angle between applied in-plane field and directions of crystallographic axes of the (Ga,Mn)As layer. Obtained results resemble the Tunneling Anisotropic Magnetoresistance (TAMR) effect discovered recently in a normal-metal-insulator-ferromagnetic-semiconductor tunneling device [2].

[1]. M. Kohda et al., Jpn. J. Appl. Phys 40, L1274 (2001).

[2]. C. Could et al., Phys. Rev. Lett. 93, 117203 (2004).