Time resolved magnetic ordering and photo-induced gyrotropy at room temperature in CdMgTe-CdMnTe semiconductor micro-cavities

Using a picosecond pump and probe time-resolved technique we evidence a single pump pulse photo-induced magnetic ordering in a Mn-doped semiconductor magneto-photonic microcavity operating in the strong coupling regime at room temperature. This nanosecond duration magnetization is attributed to a magnetic ordering of the Mn-impurities mediated through photo-generated holes and enhanced through the confinement. It is distinct from the preceding short lived photo-induced spin orientation of carriers also evidenced by our technique for circularly polarized pump beams. The photo-generated magnetic flux density amounts to a 1 kG for beam fluences of few tens μJ cm−2 and effective Mn concentrations of 5 nm−3; large photo-induced magneto-optic Kerr rotations are also evidenced.