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.

Eu2+–Eu3+ valence transition in double, Eu-, and Na-doped PbSe from transport, magnetic, and electronic structure studies

“…Such a small discrepancy is consistent with a small loss of Eu during the synthesis. Thus, in agreement with previous reports 16,18 and the small carrier …”

“…The transport properties of PbSe containing various rare-earth elements have been studied more recently. 18 In these works, Eu in PbSe was found to be electrically inactive and magnetic in the Eu 2+ state, making Pb 1Àx Eu x Se one of the dilute magnetic semiconductors (DMS). None of earlier studies include a systematic variation of both the Eu content while adjusting the p-type doping level independently, as is done here with Na-doping.…”

Higher mobility in bulk semiconductors by separating the dopants from the charge-conducting band – a case study of thermoelectric PbSe

“…35) elements has been reported by other researchers and most of these results are also included. Rare-earth elements have also been used for PbTe 36,37 or PbSe, 38,39 we found in PbSe their doping efficiency is very low…”

High-temperature thermoelectric properties ofn-type PbSe doped with Ga, In, and Pb

“…thermopower vs carrier density, at two temperatures 300 K and 700 K where filled and open symbols are used respectively. The solid line at 300 K represents the theoretical prediction for PbSe as taken from reference 32 and it shows that all systems generally agree with the expected Seebeck coefficient response. The slight deviations from theory can be attributed to our assumption of parabolic bands and unitary Hall factor in the measurement of the carrier density.…”

“…A monotonic increase with no signs of saturation is observed for all carrier densities and metal dopants throughout the temperature range of the measurements, in sharp contrast to n-type PbTe 31 which exhibits bipolar diffusion effects above 800 K and thus its performance is deteriorated. Figure 2d presents Pisarenko plots, 32 i.e. thermopower vs carrier density, at two temperatures 300 K and 700 K where filled and open symbols are used respectively.…”