SPIN TRANSPORT OF EXCITON MAGNETIC POLARONS IN DILUTED MAGNETIC SEMICONDUCTOR MULTIPLE QUANTUM WELLS. Gregory A. Balchin* and Leigh M. Smith, University of Cincinnati, Cincinnati, OH and Berry T. Jonker, Naval Research Lab, Washington, D.C. (NIST address: Building 225, Room A305, Gaithersburg, MD 20899, 301-975-6582, email: greg.balchin@nist.gov)

Spatially- and temporally-resolved photoluminescence was used to measure, for the first time, the spin transport of long-lived Type-II exciton magnetic polarons in Zn_1-xMn_xSe/ZnSe multiple quantum wells. The experimental setup involved the design and construction of a passively mode-locked Ti:Sapphire laser as well as a 20 /0.5 NA microscope objective inside a variable-temperature cryostat. We find that the free excitons diffuse very little during their 150 ps lifetime. In contrast, the effective diffusivity (D = 25 cm²/s) of the exciton magnetic polaron is 2- to 3- orders of magnitude larger than for the bare excitons. This is unexpected since the exciton magnetic polaron involves a free exciton dressed by the local polarization of the Mn-impurities, and therefore the diffusion should be less than that for the free excitons. The value of the diffusivity corresponds to an unphysically large mobility (10⁵ cm²/Vs) which may be evidence for a strong repulsive force between the exciton magnetic polarons.

*Semiconductor Electronics Division, NIST, Gaithersburg, MD