Ultrafast optical manipulation of ferromagnetic order in InMnAs/GaSb

We have performed a two-color time-resolved magneto-optical Kerr effect (MOKE) study of a ferromagnetic InMnAs/GaSb heterostructure. We observed ultrafast photo-induced changes in the MOKE signal induced by a large density of spin-polarized transient carriers created only within the InMnAs layer using intense 140 fs mid-infrared pulses. Our data clearly demonstrates that magnetic properties, e.g., remanence and coercivity, can be strongly modified. The dependence of these changes on the time delay, pump polarization, pump intensity, and sample temperature is discussed.