title: Antiferromagnetic s-d exchange coupling in GaMnAs.
abstract: Measurements of coherent electron spin dynamics in Ga1-xMnxAs/Al0.4Ga0.6As quantum wells with 0.0006%<x<0.03% show an antiferromagnetic (negative) exchange between s-like conduction band electrons and electrons localized in the d shell of the Mn2+ impurities. The magnitude of the s-d exchange parameter, N0alpha, varies as a function of well width indicative of a large and negative contribution due to kinetic exchange. In the limit of no quantum confinement, N0alpha extrapolates to -0.09+/-0.03 eV indicating that antiferromagnetic s-d exchange is a bulk property of GaMnAs. Measurements of the polarization-resolved photoluminescence show strong discrepancy from a simple model of the exchange enhanced Zeeman splitting, indicative of additional complexity in the exchange split valence band.
authors.affiliation: Center for Spintronics and Quantum Computation, University of California, Santa Barbara, California 93106, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Myers
authors.forename: M
authors.initials: M
authors.lastname: Poggio
authors.forename: N P
authors.initials: NP
authors.lastname: Stern
authors.forename: A C
authors.initials: AC
authors.lastname: Gossard
authors.forename: D D
authors.initials: DD
authors.lastname: Awschalom