Nature of magnetic coupling between Mn ions in As-grown Ga1-xMnxAs studied by x-ray magnetic circular dichroism

The magnetic properties of as-grown Ga(1-x)Mn(x)As have been investigated by the systematic measurements of temperature and magnetic field dependent soft x-ray magnetic circular dichroism (XMCD). The intrinsic XMCD intensity at high temperatures obeys the Curie-Weiss law, but a residual spin magnetic moment appears already around 100 K, significantly above the Curie temperature (T(C)), suggesting that short-range ferromagnetic correlations are developed above T(C). The present results also suggest that the antiferromagnetic interaction between the substitutional and interstitial Mn (Mn(int)) ions exists and that the amount of the Mn(int) affects T(C).