Time Resolved Magneto-Optical Studies of Ferromagnetic InMnSb Films*

Current research activities in the area of ferromagnetic semiconductor have been mainly focused on III-Mn-V alloys with small lattice constants and large effective masses of valence-band such as GaMnAs. Various theoretical models have been proposed to explain the actual mechanism of ferromagnetism in III-Mn-Vs but the microscopic mechanism is still a matter of controversy. It is therefore important to explore the opposite extreme of the III-Mn-V ternaries $i.e.$, InMnSb, which has the largest lattice constant in this family of materials. We report magneto-optical measurements in time domain of photo-induced spin and carrier in InMnSb and compare them to analogous measurements in InBeSb and InSb films. In this work, magneto-optical Kerr effect and standard pump-probe technique provided a direct measure of the photo-excited spin and carrier lifetimes, respectively. Our measurements provide new information on the dynamics and interactions in these materials systems.