Rj. Nicholas et al., A MODIFIED PHENOMENOLOGICAL DESCRIPTION OF THE EXCHANGE INTERACTIONS IN DILUTE MAGNETIC SEMICONDUCTORS, Semiconductor science and technology, 10(6), 1995, pp. 791-796
Magnetoreflectivity spectroscopy has been conducted on a series of Cd-
1-x,MnxTe epilayers (x < 0.2) in magnetic fields up to 45 T. For Mn co
ncentrations greater than a fraction of one per cent, the electronic s
p-d exchange interactions do not saturate for B > 10 T at 4.2 K, as pr
edicted by the widely used mean spin model of Gaj et al [1], but conti
nue to increase with increasing magnetic field. This is because of a f
ield-dependent increase in the total resultant spin of the dilute magn
etic sublattice, due to a reduction in the antiferromagnetic interacti
ons between the Mn2+ ions. We present a modified phenomenological desc
ription of the exchange interactions, which simply and efficiently acc
ounts for this field-induced increase in spin, necessary for an accura
te description of the high-field (B > 10 T) regime. This is achieved s
emi-empirically within the mean spin formalism, without requiring solu
tion of the complex spin Hamiltonians for double, triple and higher or
der clusters.