Effect of hydrostatic compression on the indium-impurity-induced superconducting transition in Pb0.3Sn0.7Te

Abstract

This paper reports on a study of the low-temperature conductivity and parameters of the superconducting state, namely, the critical temperature Tc and the second critical magnetic field Hc2, in the (Pb0.3Sn0.7)0.95In0.05Te solid solution under hydrostatic pressure P ≤ 9 kbar at T = 4.2 K. The choice of this material has been motivated by the fact that, according to earlier observations, it undergoes a superconducting transition at Tc ∼ 2.3 K, i.e., close to the maximum value Tc ∼ 2.9 K found for the (PbzSn1 − z)0.95In0.05Te solid solutions with a lead content z ∼ 0.15–0.25. It has been demonstrated that an increase in the pressure to P ≤ 9 kbar leads to a bell-shaped dependence Tc(P). The observed dependences are assigned to the effect of hydrostatic compression on the band structure of the solid solution and indicate a shift in the position of the Fermi level EF with increasing pressure within the impurity band of the In quasi-local states. In this case, EF passes through a maximum in the density of impurity states at P = 3–5 kbar.