Comparative study of the magnetic properties of the Yb(Gd)Te, La(Gd)Te and (La,Y)(Gd)Te solid solutions

Abstract

GdTe is a fee antiferromagnetic metal. By substituting Gd 3+ by non-magnetic divalent or trivalent rare-earth ions we generate magnetically diluted solid solutions in which the free-carrier concentration ( n) and/or the lattice parameter depend on the substitution rate. In this paper, we report on the magnetic properties of the metallic La 1− x Gd x Te solid solution where n does not depend significantly on x. The evolution of the Néel temperature with x is discussed and compared with the evolution observed in the Yb 1− x Gd x Te system, where the free-carrier concentration varies with composition. In (La 1− z Y z ) 1− x Gd x Te, we are able to control independently the free-carrier concentration and the lattice parameter. The comparison of the Néel temperature for these three solid solutions at the same Gd concentration gives evidence that the decrease of the Néel temperature vs. x in both La-based solid solutions is a pure spin-dilution effect. The fact than T N is smaller in metallic solid solutions than in Yb 1− x Gd x Te is due to a shift in the wavevector (≈ k F) of the oscillations in the Ruderman-Kittel-Kasuya-Yoshida interaction.