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Title: Doping-dependent anisotropic superconducting gap in Na1-δ(Fe1-xCox)As from London penetration depth

Abstract

The London penetration depth was measured in single crystals of self-doped Na1-δFeAs (from under doping to optimal doping, Tc from 14 to 27 K) and electron-doped Na(Fe1-xCox)As with x ranging from undoped, x=0, to overdoped, x=0.1. In all samples, the low-temperature variation of the penetration depth exhibits a power-law dependence, Δλ(T)=ATn, with the exponent that varies in a domelike fashion from n˜1.1 in the underdoped, reaching a maximum of n˜1.9 in the optimally doped, and decreasing again to n˜1.3 on the overdoped side. While the anisotropy of the gap structure follows a universal domelike evolution, the exponent at optimal doping, n˜1.9, is lower than in other charge-doped Fe-based superconductors (FeSCs). The full-temperature range superfluid density, ρs(T)=λ(0)/λ(T)2, at optimal doping is also distinctly different from other charge-doped FeSCs but is similar to isovalently substituted BaFe2(As1-xPx)2, believed to be a nodal pnictide at optimal doping. These results suggest that the superconducting gap in Na(Fe1-xCox)As is highly anisotropic even at optimal doping.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1053252
Report Number(s):
IS-J 7792
Journal ID: 0198-0121/2012/86(2)/020508(5)
DOE Contract Number:  
DE-AC02-07CH11358
Resource Type:
Journal Article
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 86; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Cho, Kyuil, Tanatar, Makariy A, Spyrison, Nicholas, Kim, Hyunsoo, Song, Y, Dai, Pengcheng, Zhang, C L, and Prozorov, Ruslan. Doping-dependent anisotropic superconducting gap in Na1-δ(Fe1-xCox)As from London penetration depth. United States: N. p., 2012. Web. doi:10.1103/PhysRevB.86.020508.
Cho, Kyuil, Tanatar, Makariy A, Spyrison, Nicholas, Kim, Hyunsoo, Song, Y, Dai, Pengcheng, Zhang, C L, & Prozorov, Ruslan. Doping-dependent anisotropic superconducting gap in Na1-δ(Fe1-xCox)As from London penetration depth. United States. doi:10.1103/PhysRevB.86.020508.
Cho, Kyuil, Tanatar, Makariy A, Spyrison, Nicholas, Kim, Hyunsoo, Song, Y, Dai, Pengcheng, Zhang, C L, and Prozorov, Ruslan. Mon . "Doping-dependent anisotropic superconducting gap in Na1-δ(Fe1-xCox)As from London penetration depth". United States. doi:10.1103/PhysRevB.86.020508.
@article{osti_1053252,
title = {Doping-dependent anisotropic superconducting gap in Na1-δ(Fe1-xCox)As from London penetration depth},
author = {Cho, Kyuil and Tanatar, Makariy A and Spyrison, Nicholas and Kim, Hyunsoo and Song, Y and Dai, Pengcheng and Zhang, C L and Prozorov, Ruslan},
abstractNote = {The London penetration depth was measured in single crystals of self-doped Na1-δFeAs (from under doping to optimal doping, Tc from 14 to 27 K) and electron-doped Na(Fe1-xCox)As with x ranging from undoped, x=0, to overdoped, x=0.1. In all samples, the low-temperature variation of the penetration depth exhibits a power-law dependence, Δλ(T)=ATn, with the exponent that varies in a domelike fashion from n˜1.1 in the underdoped, reaching a maximum of n˜1.9 in the optimally doped, and decreasing again to n˜1.3 on the overdoped side. While the anisotropy of the gap structure follows a universal domelike evolution, the exponent at optimal doping, n˜1.9, is lower than in other charge-doped Fe-based superconductors (FeSCs). The full-temperature range superfluid density, ρs(T)=λ(0)/λ(T)2, at optimal doping is also distinctly different from other charge-doped FeSCs but is similar to isovalently substituted BaFe2(As1-xPx)2, believed to be a nodal pnictide at optimal doping. These results suggest that the superconducting gap in Na(Fe1-xCox)As is highly anisotropic even at optimal doping.},
doi = {10.1103/PhysRevB.86.020508},
journal = {Physical Review B},
number = 2,
volume = 86,
place = {United States},
year = {2012},
month = {7}
}