Voltage-controlled tunneling anisotropic magnetoresistance of a ferromagnetic p++-(Ga,Mn)As∕n+-GaAs Zener-Esaki diode

The large tunneling anisotropic magnetoresistance of a ferromagnetic p++-(Ga,Mn)As∕n+-GaAs Zener-Esaki diode is shown in a perpendicular magnetic field over a large temperature and voltage range. Under an applied bias, the tunnel junction transparency is modified, allowing one to continuously tune anisotropic transport properties between the tunneling and the ohmic regimes. Furthermore, an asymmetric bias dependence of the tunneling anisotropic magnetoresistance is also observed: A reverse bias highlights the full (Ga,Mn)As valence-band states contribution, whereas a forward bias only probes part of the density of states and reveals opposite contributions from two valence subbands.