Influence of In-induced resonant level on the normal-state and superconducting properties of Sn1.03Te

Abstract

Normal-state transport properties (2–300 K) of the polycrystalline series Sn1.03−δ−xInxTe (0≤x≤0.07; δ≤0.0025) were investigated by means of electrical resistivity, thermopower, Hall effect, and thermal conductivity measurements. The distortion of the valence-band structure by the In-induced resonant level (RL) has a profound influence on the evolution of the normal-state properties with x and on the emergence of superconductivity evidenced by specific-heat measurements down to 0.35 K. In addition to a nearly 40-fold increase in the residual electrical resistivity ρ0 on going from x=0.0 to 0.05, the thermopower α shows a nonlinear, complex behavior as a function of both temperature and x. While Hall measurements indicate a dominant holelike response across the entire composition and temperature ranges, α changes sign below about 100 K and remains negative down to 5 K for 0.0015≤x≤0.0045. Additional measurements under magnetic fields μ0H of up to 14 T further shows that α(μ0H) gradually shifts towards positive values, suggestive of a dominant holelike contribution to α. Superconductivity emerges for x=0.02 at a critical temperature Tc=0.67 K, with Tc increasing with x to reach 1.73 K for x=0.07. The variations in the superconducting parameters with x, notably the specific-heat jump at Tc, confirm the results reported in prior studies and suggests a nontrivial role of the RL on the electron-phonon coupling strength. The striking similarities between this series and the canonical resonant system Pb1−xTlxTe provide an excellent experimental opportunity to gain a deeper understanding of the close interplay between resonant level, anomalous transport properties, and superconductivity.

Source-reported materials — not catalogue approval

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