Electrical magnetization reversal in ferromagnetic III–V semiconductors

Introduction of a high concentration of manganese in III?V semiconductors, such as InAs and GaAs, results in carrier-induced ferromagnetism, which allows us to integrate ferromagnetism in nonmagnetic heterostructures and which modifies their magnetic properties through electric-field control of carrier concentration. The properties of ferromagnetism can in many cases be semi-quantitatively understood by the p?d Zener model, which is qualitatively different from conventional ferromagnetic metals. These ferromagnetic III?V semiconductors also offer the unique opportunity of examining spin-dependent phenomena observed so far only in metallic systems. Here, we review our experimental study on electrical manipulation of magnetization in these ferromagnetic III?V semiconductors. We first describe the results of electrically assisted magnetization reversal in ferromagnetic semiconductor (In, Mn)As field-effect transistor structures. The coercivity as well as ferromagnetic transition temperature can be controlled through the modification of carrier concentration by applied electric fields in a gated structure. We then present electrical magnetization reversal by spin-transfer torque exerted by spin-polarized currents at low threshold current density (~105?A?cm?2) in (Ga, Mn)As-based magnetic tunnel junctions.