Magnetic properties ofPb1−xEuxTe grown by molecular-beam epitaxy

Abstract

We have measured the magnetization and magnetic susceptibility of molecular-beam-epitaxy grown ${\mathrm{Pb}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Eu}}_{\mathrm{x}}$Te with x=0.042, 0.096, 0.316, and 1.00, in the temperature range 2 K<T<300 K and for fields 0<H<4 T. The magnetic susceptibility follows a Curie-Weiss behavior: χ∼$N_{\mathrm{Eu}/(\mathrm{T}\mathrm{-}\mathrm{\Theta }}$). For all the concentrations studied, Θ is negative indicating that the Eu-Eu interaction is predominantly antiferromagnetic. However, the absolute values of Θ are 1 or 2 orders of magnitude smaller than those observed in (II,$M_n$)-VI diluted magnetic semiconductors. The magnetization can be described by a modified Brillouin function: M∼$N_{\mathrm{Eu}{}^{\mathrm{*}}\mathrm{B}\left[\right(\mathrm{T}\mathrm{-}{T}_0{)}^{\mathrm{-}1}}$] in which, for each sample, the number of Eu atoms $N_{\mathrm{Eu}{}^{\mathrm{*}}}$ and the parameter $T_0$ are nearly the same as $N_{\mathrm{Eu}}$ and Θ respectively, obtained from the susceptibility measurement. The results of the present study indicate that Eu-Eu exchange effects in ${\mathrm{Pb}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Eu}}_{\mathrm{x}}$Te are much weaker than Mn-Mn interactions in (II,$M_n$)-VI compounds.