Title: Unusual phonon density of states and response to the superconducting transition in the In-doped topological crystalline insulator ${\mathrm{Pb}}_{0.5}{\mathrm{Sn}}_{0.5}\mathrm{Te}$

Abstract

Here, we present inelastic neutron scattering results of phonons in (Pb_0.5Sn_0.5)_1–xIn_xTe powders, with x = 0, and 0.3.The x = 0 sample is a topological crystalline insulator, and the x = 0 . 3 sample is a superconductor with a bulk superconducting transition temperature T_c of 4.7 K. In both samples, we observe unexpected van Hove singularities in the phonon density of states at energies of 1– 2.5 meV, suggestive of local modes. On cooling the superconducting sample through T_c, there is an enhancement of these features for energies below twice the superconducting-gap energy. We further note that the superconductivity in (Pb_0.5Sn_0.5)_1–xIn_xTe occurs in samples with normal-state resistivities of order 10 mΩ cm, indicative of bad-metal behavior. Calculations based on density functional theory suggest that the superconductivity is easily explainable in terms of electron-phonon coupling; however, they completely miss the low-frequency modes and do not explain the large resistivity. While the bulk superconducting state of (Pb_0.5Sn_0.5)_0.7In_0.3Te appears to be driven by phonons, a proper understanding will require ideas beyond simple BCS theor

Authors:

Ran, Kejing ^[1]; Zhong, Ruidan ^[2]; Chen, Tong ^[1]; Gan, Yuan ^[1]; Wang, Jinghui ^[1]; Winn, Barry L.  ^[3];

• Search DOE PAGES for author "Winn, Barry L."
• Search DOE PAGES for ORCID "0000-0001-6383-4318"

Christianson, Andrew D.  ^[3];

• Search DOE PAGES for author "Christianson, Andrew D."
• Search DOE PAGES for ORCID "0000-0003-3369-5884"

Li, Shichao ^[1]; Ma, Zhen ^[1]; Bao, Song ^[1]; Cai, Zhengwei ^[1]; Xu, Guangyong ^[4]; Tranquada, J. M. ^[4]; Gu, Genda ^[4]; Sun, Jian ^[5]; Wen, Jinsheng ^[5]

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+ Show Author Affiliations

1. Nanjing Univ. (China). National Lab. of Solid State Microstructures and Dept. of Physics
2. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.; Stony Brook Univ., NY (United States). Materials Science and Engineering Dept.
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Neutron Scattering Division
4. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.
5. Nanjing Univ. (China). National Lab. of Solid State Microstructures and Dept. of Physics; Nanjing Univ. (China). Collaborative Innovation Center of Advanced Microstructures

Publication Date:

Fri Jun 15 00:00:00 EDT 2018

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Emergent Superconductivity (CES); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1462866

Alternate Identifier(s):

OSTI ID: 1440352; OSTI ID: 1454370

Report Number(s):

BNL-205733-2018-JAAM
Journal ID: ISSN 2469-9950; PRBMDO; TRN: US1902221

Grant/Contract Number:  

AC05-00OR22725; SC0012704; 2009-BNL-PM015

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review B

Additional Journal Information:

Journal Volume: 97; Journal Issue: 22; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Electron-phonon coupling; Superconductivity; Density functional theory; First-principles calculations; Inelastic neutron scattering