Photomagnetic effects in III–V based magnetic semiconductors

Experimental results on the optical excitation of the III–V based magnetic semiconductor epilayers and related inhomogeneous systems are reviewed. Dynamic behaviors of optically induced magnetization rotation in the hole-mediated ferromagnetic semiconductor (Ga,Mn)As are discussed in terms of the newly proposed coupled hole-Mn spin complex for which hole and Mn spins rotate and relax together upon the optical excitation. Large photo-induced polar Kerr effect in the (Ga,Mn)As quantum wells, suggesting the enhanced magnetization rotation, is disclosed, from which manipulation of ferromagnetism through the dimensionality control of electronic states is discussed. Partial magnetization reversal by the electrical injection of hole spins has also been discussed on the basis of experimental results obtained from the (Ga,Mn)As-based magnetic tunnel junction devices. As to the room-temperature photo-enhanced magnetization (PEM) in the GaAs–Fe system, we found that the origin of PEM in the recently developed films is originated, at least partially, from the light-induced heating of the metamagnet Fe3Ga4. The contribution of photon-mode PEM is also discussed based on the experimental data.