Campus Units
Materials Science and Engineering, Physics and Astronomy, Ames Laboratory
Document Type
Article
Publication Version
Published Version
Publication Date
9-30-2016
Journal or Book Title
Science Advances
Volume
2
Issue
9
First Page
e1600807
DOI
10.1126/sciadv.1600807
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, (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. 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.
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Copyright Owner
The Authors
Copyright Date
2016
Language
en
File Format
application/pdf
Recommended Citation
Cho, Kyuil; Kończykowski, 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" (2016). Ames Laboratory Publications. 416.
https://lib.dr.iastate.edu/ameslab_pubs/416
Comments
This article is published as Cho, Kyuil, Marcin Kończykowski, Serafim Teknowijoyo, Makariy A. Tanatar, Yong Liu, Thomas A. Lograsso, Warren E. Straszheim et al. "Energy gap evolution across the superconductivity dome in single crystals of (Ba1− xKx) Fe2As2." Science Advances 2, no. 9 (2016): e1600807. DOI: 10.1126/sciadv.1600807. Posted with permission.