Low-energy phonons and superconductivity inSn0.8In0.2Te

Abstract

We present neutron scattering measurements on low-energy phonons from a superconducting (Tc = 2.7 K) Sn0.8In0.2Te single crystal sample. The longitudinal acoustic phonon mode and one transverse acoustic branch have been mapped out around the (002) Bragg peak for temperatures of 1.7 K and 4.2 K. We observe a substantial energy width of the transverse phonons at energies comparable to twice the superconducting gap; however, there is no change in this width between the superconducting and normal states, and the precise origin of this energy width anomaly is not entirely clear. We also confirm that the compound is well ordered, with no indications of structural instability.

Electron-phonon coupling and superconductivity in the doped topological-crystalline insulator (Pb$_{0.5}$Sn$_{0.5}$)$_{1-x}$In$_x$Te

“…Looking back at measurements of phonon line widths in the related superconductor, Sn 0.8 In 0.2 Te, broadening of TA phonons at small q was observed. 61 This would be consistent with coupling to the soft zone-center TO and LO modes. To the extent that it involves electron coupling, it would suggest an interaction that involves electrons on the same small Fermi pocket, and not "intervalley" interactions (scattering between pockets) as originally proposed.…”

Enhanced superconducting transition temperatures in the rocksalt-type superconductors In1−xSnxTe (x≤0.5Kobayashi1, Ai2, Jeschke3 et al. 2018Phys. Rev. B206170View full textAdd to dashboardCite

“…The latter experiment detects two acoustic phonon modes consistent with those of the parent SnTe [33]. The transverse optical phonon mode is linked to superconductivity, to the structural transition, and to ferroelectricity in SnTe [32], and may be expected to play an important role in the In-doped compound as well [33]. Despite the gradual change of T c , H c2 (0) drops drastically at x = 0 (InTe) as shown in Table I.…”

“…Even though we could not perform a detailed study to determine the phonon spectrum, there are several neutron-scattering measurements for single crystals of SnTe [32] and the In-doped compound Sn 0.8 In 0.2 Te [32]. The latter experiment detects two acoustic phonon modes consistent with those of the parent SnTe [33]. The transverse optical phonon mode is linked to superconductivity, to the structural transition, and to ferroelectricity in SnTe [32], and may be expected to play an important role in the In-doped compound as well [33].…”

Electron and hole contributions to normal-state transport in the superconducting system Sn1−xInxTe

“…It was noted quite some time ago that the non-ionic bonding character of IV-VI compounds with the rock salt structure leads to a significant electron-phonon interaction [41,42]. Indeed, an enhanced damping has been observed for low-energy transverse acoustic phonons in Sn 0.8 In 0.2 Te [43]. What role does the strong electronic polarizability play in the localization/delocalization of the In 5s states, and how does this relate to evidence for strong-coupling superconductivity [23]?…”