Magnetic properties of Pb1-xEuxTe grown by molecular-beam epitaxy.

Abstract

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