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Title: Superconducting energy gap of 2 H - NbS e 2 in phonon spectroscopy

Abstract

We present a high-energy-resolution inelastic x-ray scattering data investigation of the charge-density-wave (CDW) soft phonon mode upon entering the superconducting state in 2 H–NbSe 2. Measurements were done close to the CDW ordering wave vector qCDW at q=q CDW + (0,0,l), 0.15 ≤ l ≤ 0.5, for T = 10K (CDW order) and 3.8K (CDW order+superconductivity). We observe changes of the phonon line shape that are characteristic for systems with strong electron-phonon coupling in the presence of a superconducting energy gap 2Δ c and from which we can demonstrate an l dependence of the superconducting gap. Reversely, our data imply that the CDW energy gap is strongly localized along the c* direction. The confinement of the CDW gap to a very small momentum region explains the rather low competition and easy coexistence of CDW order and superconductivity in 2 H–NbSe 2. Furthermore, the energy gained by opening Δ CDW seems to be too small to be the driving force of the phase transition at T CDW = 33K, which is better described as an electron-phonon coupling driven structural phase transition.

Authors:
 [1];  [2];  [1];  [2]
  1. Karlsruhe Institute of Technology, Karlsruhe (Germany)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Materials Sciences and Engineering Division; Helmholtz Association
OSTI Identifier:
1352563
Alternate Identifier(s):
OSTI ID: 1329985
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 14; 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

Citation Formats

Weber, F., Rosenkranz, S., Heid, R., and Said, A. H. Superconducting energy gap of 2H-NbSe2 in phonon spectroscopy. United States: N. p., 2016. Web. doi:10.1103/PhysRevB.94.140504.
Weber, F., Rosenkranz, S., Heid, R., & Said, A. H. Superconducting energy gap of 2H-NbSe2 in phonon spectroscopy. United States. doi:10.1103/PhysRevB.94.140504.
Weber, F., Rosenkranz, S., Heid, R., and Said, A. H. Tue . "Superconducting energy gap of 2H-NbSe2 in phonon spectroscopy". United States. doi:10.1103/PhysRevB.94.140504. https://www.osti.gov/servlets/purl/1352563.
@article{osti_1352563,
title = {Superconducting energy gap of 2H-NbSe2 in phonon spectroscopy},
author = {Weber, F. and Rosenkranz, S. and Heid, R. and Said, A. H.},
abstractNote = {We present a high-energy-resolution inelastic x-ray scattering data investigation of the charge-density-wave (CDW) soft phonon mode upon entering the superconducting state in 2H–NbSe2. Measurements were done close to the CDW ordering wave vector qCDW at q=qCDW + (0,0,l), 0.15 ≤ l ≤ 0.5, for T = 10K (CDW order) and 3.8K (CDW order+superconductivity). We observe changes of the phonon line shape that are characteristic for systems with strong electron-phonon coupling in the presence of a superconducting energy gap 2Δc and from which we can demonstrate an l dependence of the superconducting gap. Reversely, our data imply that the CDW energy gap is strongly localized along the c* direction. The confinement of the CDW gap to a very small momentum region explains the rather low competition and easy coexistence of CDW order and superconductivity in 2H–NbSe2. Furthermore, the energy gained by opening ΔCDW seems to be too small to be the driving force of the phase transition at TCDW = 33K, which is better described as an electron-phonon coupling driven structural phase transition.},
doi = {10.1103/PhysRevB.94.140504},
journal = {Physical Review B},
number = 14,
volume = 94,
place = {United States},
year = {Tue Oct 25 00:00:00 EDT 2016},
month = {Tue Oct 25 00:00:00 EDT 2016}
}

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Works referenced in this record:

Strongly enhanced charge-density-wave order in monolayer NbSe2
journal, July 2015

  • Xi, Xiaoxiang; Zhao, Liang; Wang, Zefang
  • Nature Nanotechnology, Vol. 10, Issue 9, p. 765-769
  • DOI: 10.1038/nnano.2015.143