Enhanced superconducting transition temperatures in the rocksalt-type superconductors In1−xSnxTe (x≤0.5

Abstract

We investigate superconductivity in In 1−x Sn x Te (x 0.5) synthesized at high pressures of up to 2 GPa and observe an enhancement of the superconducting transition temperature T c for increasing tin concentration x. These compounds have not been accessible in rocksalt structure via conventional ambient pressure synthesis. While the lattice constant smoothly increases with x, T c saturates around x = 0.4. Electronic structure calculations indicate that the T c modulation is brought on by the change of the density of states in the vicinity of the Fermi energy [N (E F)]. However, differences between the calculated N (E F) and the observed electronic specific-heat coefficient indicate that the phonon dispersion plays an important role in the system and that the mechanism of superconductivity may not be the same in the entire doping range.

Superconductivity in In-doped AgSnBiTe3 with possible band inversion

“…As shown in Fig. 3d, the lattice constant decreases with increasing y, which is a trend similar to other In-doped M-Te systems 8,12 . The actual element concentrations of the samples were examined by energydispersive X-ray spectroscopy (EDX), and the results are shown in Fig.…”

“…The superconducting jump in Cel (ΔCel) estimated with Tc = 2.16 K is 1.34γTc, which is comparable to the value expected from a full-gap superconductivity based on the BCS model (ΔCel = 1.43γTc) 27 . Those values obtained from specific heat are similar to those obtained for In-doped SnTe and Ag-doped SnTe superconductors with 20% In (or Ag) doping 8,28 . To investigate the In-doping dependence of superconducting states, temperature dependences of magnetic susceptibility (4πχ) was measured for (AgSnBi)(1-y)/3InyTe.…”

“…Seeing lattice constants for In-doped samples, we find that the lattice constant is smaller than the end member of InTe with a ~ 6.175 Å 8 . Therefore, we consider that the suppression of superconductivity observed for y = 0.5 is due to the increase in inhomogeneity in the sample, and the solution limit of In for AgSnBiTe3 is around y = 0.4 under pressures up to 2 GPa.…”

“…Having looked at the phase diagrams of (Sn,In)Te and (Pb,In)Te 8,12 , superconductivity is observed in a wide range of In concentration. As shown in Fig.…”

“…Metal tellurides (MTe) with a NaCl-type structure have been extensively studied due to their physical properties as topological materials [1][2][3][4] , thermoelectric materials [5][6][7] , and superconductors [8][9][10][11][12] . Among them, In-doped SnTe superconductors have been drawing attention as a candidate system of a topological superconductor 4,[13][14][15][16][17] .…”