X-ray absorption spectroscopy (XAS) and XMCD measurements reveal induced host magnetic
moments in Mn-doped GaAs ferromagnets. These materials are of great interest for devices
utilizing the electron spin as well as its charge (spintronics). Theories
predict that Mn ions induce polarized valence band states which mediate the magnetic
coupling, resulting in small magnetic moments on the semiconductor host
elements. XMCD at the Mn, Ga, and As L edges in a 7% Mn-doped GaAs show induced moments
at the Ga and As sites with 4s orbital character. Selection rules indicate that the As moment
is larger than the Ga moment, and that all moments align as predicted by
the valence-band hole coupling mechanism. [Phys. Rev. Lett. 91, 187203 (2003)].
Local Contact: Dave Keavney (
keavney@aps.anl.gov)
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