Role of defect sites and Ga polarization in the magnetism of Mn-doped GaN.
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.
Keavney
D J
DJ
Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Cheung
S H
SH
King
S T
ST
Weinert
M
M
Li
L
L