Quasiparticle heat transport in single-crystalline Ba(1-x)KxFe(2)As(2): Evidence for a k-dependent superconducting gap without nodes
Date
2009-10-01
Authors
Luo, X. G.
Tanatar, M. A.
Reid, J. -Ph.
Shakeripour, H.
Doiron-Leyraud, N.
Ni, Ni
Bud'ko, Sergey L.
Luo, Huiqian
Wang, Zhaosheng
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American Physical Society
Abstract
The thermal conductivity kappa of the iron-arsenide superconductor Ba1-xKxFe2As2 (T-c similar or equal to 30 K) was measured in single crystals at temperatures down to T not similar or equal to 50 mK (similar or equal to T-c/600) and in magnetic fields up to H = 15 T(similar or equal to H-c2/4). A negligible residual linear term in kappa/T as T -> 0 shows that there are no zero-energy quasiparticles in the superconducting state. This rules out the existence of line and in-plane point nodes in the superconducting gap, imposing strong constraints on the symmetry of the order parameter. It excludes d-wave symmetry, drawing a clear distinction between these superconductors and the high-T-c cuprates. However, the fact that a magnetic field much smaller than H-c2 can induce a residual linear term indicates that the gap must be very small on part of the Fermi surface, whether from strong anisotropy or band dependence, or both.
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This article is published as Luo, X. G., M. A. Tanatar, J-Ph Reid, H. Shakeripour, N. Doiron-Leyraud, N. Ni, S. L. Bud’Ko et al. "Quasiparticle heat transport in single-crystalline Ba 1− x K x Fe 2 As 2: Evidence for a k-dependent superconducting gap without nodes." Physical Review B 80, no. 14 (2009): 140503.
DOI: 10.1103/PhysRevB.80.140503.
Copyright 2009 American Physical Society.
Posted with permission.