  The prototypical diluted magnetic semiconductor Cd1-xMnxTe is a spin glass
(x<0.6) or an antiferromagnet (x>0.6), but becomes ferromagnetic upon doping
with a small amount of Cr atoms substituting for Mn. In order to investigate
the origin of the ferromagnetism in Cd1-x-yMnxCryTe, we have studied its
element specific magnetic properties by x-ray absorption spectroscopy (XAS) and
x-ray magnetic circular dichroism (XMCD) at the Cr and Mn L2,3 edges. Thin
films were grown by molecular beam epitaxy with a fixed Mn content of x = 0.2
and varying Cr content in the range of y = 0 - 0.04. Measured XAS and XMCD
spectra indicate that both Cr and Mn atoms are divalent and that the
ferromagnetic or superparamagnetic components of Cr and Mn are aligned in the
same directions. The magnetization of Mn increases with increasing Cr content.
These results can be explained if ferromagnetic interaction exists between
neighboring Mn and Cr ions although interaction between Mn atoms is largely
antiferromagnetic. We conclude that each ferromagnetic or superparamagnetic
cluster consists of ferromagnetically coupled several Cr and a much larger
number of Mn ions.
