Voltage-controlled tunneling anisotropic magneto-resistance of a ferromagnetic $p^{++}$-(Ga,Mn)As/$n^{+}$-GaAs Zener-Esaki diode

摘要

The large tunneling anisotropic magneto-resistance of a single$p^{++}$-(Ga,Mn)As/$n^{+}$-GaAs Zener-Esaki diode is evidenced in aperpendicular magnetic field over a large temperature and voltage range. Underan applied bias, the tunnel junction transparency is modified, allowing tocontinuously tune anisotropic transport properties between the tunneling andthe ohmic regimes. Furthermore, an asymmetric bias-dependence of theanisotropic tunneling magneto-resistance is also observed: a reverse biashighlights the full (Ga,Mn)As valence band states contribution, whereas aforward bias only probes part of the density of states and reveals oppositecontributions from two subbands.