Effect of low-level Ge additions on the superconducting transition in PbTe:Tl

Abstract

A study is reported of the effect of low-level germanium additions (∼0.01–0.1 at. %) on the parameters of the superconducting transition, viz. the critical temperature T _c, the second critical magnetic field H _c2, and $\left| {{{dH_{c2} } \mathord{\left/ {\vphantom {{dH_{c2} } {dT}}} \right. \kern-\nulldelimiterspace} {dT}}} \right|_{T \to T_c }$ in PbTe doped with 2 at. % Tl, which are derived from the dependence of the electrical resistivity of a sample on temperature (0.4–4.2 K) and magnetic field (0–1.3 T). The discontinuity revealed by experimental data is related to the onset of a Ge-induced structural phase transition.