Transport and magnetic properties of dilute rare-earth–PbSe alloys

Abstract

Polycrystalline alloys of PbSe with rare-earth elements (Ce, Pr, Nd, Eu, Gd, and Yb) have been prepared and their magnetic susceptibility (from 4 to 120 K), galvanomagnetic and thermomagnetic transport (from 80 to 380 K) properties have been measured. Most samples are paramagnetic, and the concentration of rare-earth atoms in the PbSe lattice is deduced from fitting a Curie-Weiss law. The electrical conductivity, Hall, Seebeck, and transverse Nernst-Ettingshausen effects are interpreted in terms of the carrier density and mobility, the density of states effective mass, and the scattering exponent. In summary, Pb1−xEuxSe is a semiconductor with a wider gap than PbSe, but the carrier density is unaffected by the presence of Eu. The other rare earths, which are essentially trivalent atoms, act as donors, with a doping efficiency close to unity in the case of Ce and Nd, but much less for Gd and Yb. The mechanisms that govern the observed decrease in mobility are also discussed.