Influence of pair-exchange interaction on the magnetization of IV-VI-compound diluted magnetic semiconductors

Abstract

The magnetization of IV-VI-compound diluted magnetic semiconductor systems has been measured at 4.2 K with use of the sample-extraction method in steady magnetic fields up to 30 T. The results have been fitted by an expression containing a Brillouin function, representing isolated magnetic ions, plus a term representing pair interactions. The fitting parameters are x${\ifmmode\bar\else\textasciimacron\fi{}}_{1}$, the effective occupation probability of a cation site by a Mn ion; ${T}_{0}$, representing the exchange interaction between ${\mathrm{Mn}}^{2+}$ ions; x${\ifmmode\bar\else\textasciimacron\fi{}}_{2}$, representing the number of ${\mathrm{Mn}}^{2+}$ ions in pairs; and ${J}_{P}$, a pair-exchange parameter. Reasonable agreement of these high-field parameters with parameters obtained from the low-field susceptibility was obtained. Fits including the nearest-neighbor-pair--exchange function confirm the importance of nearest-neighbor pairs in the antiferromagnetic exchange interaction.