Sa. Crooker et al., TIME-RESOLVED FARADAY-ROTATION SPECTROSCOPY OF SPIN DYNAMICS IN DIGITAL MAGNETIC HETEROSTRUCTURES, IEEE journal of selected topics in quantum electronics, 1(4), 1995, pp. 1082-1092
A time-resolved resonant Faraday rotation spectroscopy is employed to
study the dynamical interplay between local magnetic moments and photo
excited carrier spins in quantum-confined semiconductor geometries, Th
is highly sensitive technique functions as an energy selective, noninv
asive, all-optical probe of spin dynamics ranging from femtosecond to
microsecond timescales and is particularly suited to low-dimensional s
ystems having small numbers of magnetic spins. Carrier spin-scattering
rates, lifetimes, and the orientation and relaxation of perturbed mag
netic ions are directly observed in the time domain, The utility of th
is technique is demonstrated through the study of a newly developed cl
ass of magnetic heterostructure, in which fractional monolayer planes
of magnetic Mn2+ ions are incorporated ''digitally'' into nonmagnetic
II-VI ZnSe-ZnCdSe quantum wells. These digital magnetic heterostructur
es (DMH) possess large g-factors and exhibit enormous low-field resona
nt Faraday rotations in excess of 1.7 x 10(7) deg/T.cm at low temperat
ures. Time-resolved Faraday rotation measurements identify a wealth of
unexpected electronic and magnetic spin dynamics that are different f
rom those generated in traditional semiconductors or alloyed diluted m
agnetic semiconductor structures.