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Title: Energy gap evolution across the superconductivity dome in single crystals of (Ba 1-xK x)Fe 2As 2

Abstract

The mechanism of unconventional superconductivity in iron-based superconductors (IBSs) is one of the most intriguing questions in current materials research. Among non-oxide IBSs, (Ba 1$-$xK x)Fe 2As 2 has been intensively studied because of its high superconducting transition temperature and fascinating evolution of the superconducting gap structure from being fully isotropic at optimal doping (x ≈ 0.4) to becoming nodal at x > 0.8. Although this marked evolution was identified in several independent experiments, there are no details of the gap evolution to date because of the lack of high-quality single crystals covering the entire K-doping range of the superconducting dome. In this work, we conducted a systematic study of the London penetration depth, λ(T), across the full phase diagram for different concentrations of point-like defects introduced by 2.5-MeV electron irradiation. Fitting the low-temperature variation with the power law, Δλ ~ T n, we find that the exponent n is the highest and the Tc suppression rate with disorder is the smallest at optimal doping, and they evolve with doping being away from optimal, which is consistent with increasing gap anisotropy, including an abrupt change around x ≃ 0.8, indicating the onset of nodal behavior. Our analysis using a self-consistentmore » t-matrix approach suggests the ubiquitous and robust nature of s ± pairing in IBSs and argues against a previously suggested transition to a d-wave state near x = 1 in this system.« less

Authors:
 [1];  [2];  [1];  [1];  [3];  [4];  [3];  [5];  [6];  [6];  [1]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy
  2. Ecole Polytechnique and Univ. Paris-Saclay, Palaiseau (France). Lab. of Irradiated Solids (LSI)
  3. Ames Lab., Ames, IA (United States)
  4. Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Materials Science and Engineering
  5. Univ. of Tennessee, Knoxville, TN (United States). Joint Inst. for Computational Sciences; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
  6. Univ. of Florida, Gainesville, FL (United States). Dept. of Physics
Publication Date:
Research Org.:
Ames Lab., Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1342931
Report Number(s):
IS-J-9048
Journal ID: ISSN 2375-2548
Grant/Contract Number:  
AC02-07CH11358; NSF-DMR-1005625
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Science Advances
Additional Journal Information:
Journal Volume: 2; Journal Issue: 9; Journal ID: ISSN 2375-2548
Publisher:
AAAS
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; IBSs; iron-based superconductors

Citation Formats

Cho, Kyuil, Konczykowski, Marcin, Teknowijoyo, Serafim, Tanatar, Makariy A., Liu, Yong, Lograsso, Thomas A., Straszheim, Warren E., Mishra, Vivek, Maiti, Saurabh, Hirschfeld, Peter J., and Prozorov, Ruslan. Energy gap evolution across the superconductivity dome in single crystals of (Ba1-xKx)Fe2As2. United States: N. p., 2016. Web. doi:10.1126/sciadv.1600807.
Cho, Kyuil, Konczykowski, Marcin, Teknowijoyo, Serafim, Tanatar, Makariy A., Liu, Yong, Lograsso, Thomas A., Straszheim, Warren E., Mishra, Vivek, Maiti, Saurabh, Hirschfeld, Peter J., & Prozorov, Ruslan. Energy gap evolution across the superconductivity dome in single crystals of (Ba1-xKx)Fe2As2. United States. doi:10.1126/sciadv.1600807.
Cho, Kyuil, Konczykowski, Marcin, Teknowijoyo, Serafim, Tanatar, Makariy A., Liu, Yong, Lograsso, Thomas A., Straszheim, Warren E., Mishra, Vivek, Maiti, Saurabh, Hirschfeld, Peter J., and Prozorov, Ruslan. Fri . "Energy gap evolution across the superconductivity dome in single crystals of (Ba1-xKx)Fe2As2". United States. doi:10.1126/sciadv.1600807. https://www.osti.gov/servlets/purl/1342931.
@article{osti_1342931,
title = {Energy gap evolution across the superconductivity dome in single crystals of (Ba1-xKx)Fe2As2},
author = {Cho, Kyuil and Konczykowski, Marcin and Teknowijoyo, Serafim and Tanatar, Makariy A. and Liu, Yong and Lograsso, Thomas A. and Straszheim, Warren E. and Mishra, Vivek and Maiti, Saurabh and Hirschfeld, Peter J. and Prozorov, Ruslan},
abstractNote = {The mechanism of unconventional superconductivity in iron-based superconductors (IBSs) is one of the most intriguing questions in current materials research. Among non-oxide IBSs, (Ba1$-$xKx)Fe2As2 has been intensively studied because of its high superconducting transition temperature and fascinating evolution of the superconducting gap structure from being fully isotropic at optimal doping (x ≈ 0.4) to becoming nodal at x > 0.8. Although this marked evolution was identified in several independent experiments, there are no details of the gap evolution to date because of the lack of high-quality single crystals covering the entire K-doping range of the superconducting dome. In this work, we conducted a systematic study of the London penetration depth, λ(T), across the full phase diagram for different concentrations of point-like defects introduced by 2.5-MeV electron irradiation. Fitting the low-temperature variation with the power law, Δλ ~ Tn, we find that the exponent n is the highest and the Tc suppression rate with disorder is the smallest at optimal doping, and they evolve with doping being away from optimal, which is consistent with increasing gap anisotropy, including an abrupt change around x ≃ 0.8, indicating the onset of nodal behavior. Our analysis using a self-consistent t-matrix approach suggests the ubiquitous and robust nature of s± pairing in IBSs and argues against a previously suggested transition to a d-wave state near x = 1 in this system.},
doi = {10.1126/sciadv.1600807},
journal = {Science Advances},
issn = {2375-2548},
number = 9,
volume = 2,
place = {United States},
year = {2016},
month = {9}
}

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    Works referencing / citing this record:

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    Electronic properties, low-energy Hamiltonian, and superconducting instabilities in CaKFe 4 As 4
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