Magnetic manifestations of carrier localization in quantum well

Abstract

The authors report a direct study of the optically induced magnetism in a semiconductor quantum well system, to explore the connection between the electronic and magnetic properties of these heterostructures. The experiments use Cd1-x Mnx Te-Cd 1-y Mny Te superlattice structures, which are excited optically by picosecond pulses. The magnetism is induced by the optically generated carriers through a local spin-spin exchange interaction with the magnetic moments. Time-averaged magnetic spectroscopy measurements reveal a connection between the quantum confinement of the electrons and holes and the magnetic properties through the appearance of a well-defined structure in the spectra. The time-resolved behavior of this magnetization is critically dependent on the width of the quantum well and the energy of the confined carriers, in that the magnetic relaxation time rapidly decreases with advancing penetration of the carrier wave functions into the nearby barriers.