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Title: Andreev spectroscopy of FeSe: Evidence for two-gap superconductivity

Abstract

Current-voltage characteristics (CVCs) of Andreev superconductor-constriction-superconductor (ScS) contacts in polycrystalline samples of FeSe with the critical temperature T{sub C} = (12 {+-} 1) K have been measured using the break-junction technique. In Sharvin-type nanocontacts, two sets of subharmonic gap structures were detected due to multiple Andreev reflections, indicating the existence of two nodeless superconducting gaps {Delta}{sub L} = (2.75 {+-} 0.3) meV and {Delta}{sub S} = (0.8 {+-} 0.2) meV. Well-shaped CVCs for stacks of Andreev contacts with up to five contacts were observed due to the layered structure of FeSe (the intrinsic multiple Andreev reflections effect). An additional fine structure in the CVCs of Andreev ScS nanocontacts is attributed to the existence of a Leggett mode. A linear relation between the superconducting gap {Delta}{sub L} and the magnetic resonance energy E{sub magres} Almost-Equal-To 2{Delta}{sub L} is found to be valid for layered iron pnictides.

Authors:
; ; ; ; ; ; ;  [1];  [2]
  1. Moscow State University, Low Temperature Physics and Superconductivity Department (Russian Federation)
  2. Institut fur Festkoerperphysik, Karlsruher Institut fuer Technologie (Germany)
Publication Date:
OSTI Identifier:
22028021
Resource Type:
Journal Article
Journal Name:
Journal of Experimental and Theoretical Physics
Additional Journal Information:
Journal Volume: 113; Journal Issue: 3; Other Information: Copyright (c) 2011 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1063-7761
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRITICAL TEMPERATURE; FINE STRUCTURE; IRON SELENIDES; MAGNETIC RESONANCE; NANOSTRUCTURES; PNICTIDES; POLYCRYSTALS; REFLECTION; SPECTROSCOPY; SUPERCONDUCTIVITY; SUPERCONDUCTORS

Citation Formats

Ponomarev, Ya. G., Kuzmichev, S. A., Mikheev, M. G., Sudakova, M. V., Tchesnokov, S. N., Shanygina, T. E., Volkova, O. S., Vasiliev, A. N., E-mail: vasil@mig.phys.msu.ru, and Wolf, Th. Andreev spectroscopy of FeSe: Evidence for two-gap superconductivity. United States: N. p., 2011. Web. doi:10.1134/S1063776111080097.
Ponomarev, Ya. G., Kuzmichev, S. A., Mikheev, M. G., Sudakova, M. V., Tchesnokov, S. N., Shanygina, T. E., Volkova, O. S., Vasiliev, A. N., E-mail: vasil@mig.phys.msu.ru, & Wolf, Th. Andreev spectroscopy of FeSe: Evidence for two-gap superconductivity. United States. doi:10.1134/S1063776111080097.
Ponomarev, Ya. G., Kuzmichev, S. A., Mikheev, M. G., Sudakova, M. V., Tchesnokov, S. N., Shanygina, T. E., Volkova, O. S., Vasiliev, A. N., E-mail: vasil@mig.phys.msu.ru, and Wolf, Th. Thu . "Andreev spectroscopy of FeSe: Evidence for two-gap superconductivity". United States. doi:10.1134/S1063776111080097.
@article{osti_22028021,
title = {Andreev spectroscopy of FeSe: Evidence for two-gap superconductivity},
author = {Ponomarev, Ya. G. and Kuzmichev, S. A. and Mikheev, M. G. and Sudakova, M. V. and Tchesnokov, S. N. and Shanygina, T. E. and Volkova, O. S. and Vasiliev, A. N., E-mail: vasil@mig.phys.msu.ru and Wolf, Th.},
abstractNote = {Current-voltage characteristics (CVCs) of Andreev superconductor-constriction-superconductor (ScS) contacts in polycrystalline samples of FeSe with the critical temperature T{sub C} = (12 {+-} 1) K have been measured using the break-junction technique. In Sharvin-type nanocontacts, two sets of subharmonic gap structures were detected due to multiple Andreev reflections, indicating the existence of two nodeless superconducting gaps {Delta}{sub L} = (2.75 {+-} 0.3) meV and {Delta}{sub S} = (0.8 {+-} 0.2) meV. Well-shaped CVCs for stacks of Andreev contacts with up to five contacts were observed due to the layered structure of FeSe (the intrinsic multiple Andreev reflections effect). An additional fine structure in the CVCs of Andreev ScS nanocontacts is attributed to the existence of a Leggett mode. A linear relation between the superconducting gap {Delta}{sub L} and the magnetic resonance energy E{sub magres} Almost-Equal-To 2{Delta}{sub L} is found to be valid for layered iron pnictides.},
doi = {10.1134/S1063776111080097},
journal = {Journal of Experimental and Theoretical Physics},
issn = {1063-7761},
number = 3,
volume = 113,
place = {United States},
year = {2011},
month = {9}
}