Spin dynamics of Mn-ion system in diluted-magnetic-semiconductor heterostructures based on ZnMnSe

摘要

A comprehensive study of a spin-lattice relaxation dynamics of magnetic Mn-ions in DMS quantum wells based on ZnMnSe is reported. We exploit an internal thermometer of the Mn spin temperature, which is provided by the high sensitivity of the giant Zeeman splitting of excitons (band states) to the polarization of the magnetic Mn-ions. The spin-lattice relaxation time varies by five orders of magnitude from 10–3s down to 10–8s, when the Mn content increases from 0.4% up to 11%. We establish an important role of free carriers in the heating of the Mn system, by its interaction with photoexcited carriers with excess kinetic energy, and in the cooling of the Mn system in the presence of cold background carriers provided by modulation doping. For Zn0.89Mn0.11Se quantum well structures, where the spin-lattice relaxation process is considerably faster the characteristic lifetimes of nonequilibrium phonons, the phonon dynamics and it contribution to the heating of the Mn system is investigated.