Valence band orbital polarization in III-V ferromagnetic semiconductors

Authors :: Freeman, A. A.
Edmonds, K. W.
van der Laan, G.
Campion, R. P.
Farley, N. R. S.
Rushforth, A. W.
Johal, T. K.
Foxon, C. T.
Gallagher, B. L.
Rogalev, A.
Wilhelm, F.
Publication Year :: 2008
Abstract: The element-specific technique of x-ray magnetic circular dichroism (XMCD) is used to directly determine the magnitude and character of the valence band orbital magnetic moments in (III,Mn)As ferromagnetic semiconductors. A distinct dichroism is observed at the As K absorption edge, yielding an As 4p orbital magnetic moment of around -0.1 Bohr magnetons per valence band hole. This is strongly influenced by strain, indicating its crucial influence on the magnetic anisotropy. The dichroism at the Ga K edge is much weaker. The K edge XMCD signals for Mn and As both have positive sign, which indicates the important contribution of Mn 4p states to the Mn K edge spectra.<br />Comment: 5 pages, 2 figures