title: Role of defect sites and Ga polarization in the magnetism of Mn-doped GaN.
abstract: We report a study of the Mn local structure, magnetism, and Ga moments in molecular beam epitaxy grown Mn-doped GaN films. Using x-ray absorption spectroscopy and magnetic circular dichroism, we find two distinct Mn sites and a Ga moment antiparallel to Mn. First-principles calculations reproduce this phenomenology and indicate that Mn preferentially populates Ga sites neighboring N split interstitial defects. These results show that defects may strongly affect the Mn ordering and magnetism, and that the GaN valence band is polarized, providing a long-range ferromagnetic ordering mechanism for Ga1-xMnxN.
authors.affiliation: Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Keavney
authors.forename: S H
authors.initials: SH
authors.lastname: Cheung
authors.forename: S T
authors.initials: ST
authors.lastname: King
authors.forename: M
authors.initials: M
authors.lastname: Weinert
authors.forename: L
authors.initials: L
authors.lastname: Li