Title: Experimental evidence for a two-gap structure of superconducting NbSe(2): A specific-heat study in external magnetic fields
Authors: Huang, C. L.
Lin, J. -Y.
Chang, Y. T.
Sun, C. P.
Shen, H. Y.
Chou, C. C.
Berger, H.
Lee, T. K.
Yang, H. D.
Institute of Physics
Issue Date: 1-Dec-2007
Abstract: To resolve the discrepancies of the superconducting order parameter in quasi-two-dimensional NbSe(2), comprehensive specific-heat measurements have been carried out. By analyzing both the zero-field and mixed-state data with magnetic fields perpendicular (H perpendicular to c) to and parallel (H parallel to c) to the c axis of the crystal and using the two-gap model, we conclude that (1) more than one energy scale of the order parameter is required for superconducting NbSe(2) due to the thermodynamic consistency; (2) Delta(L)=1.26 meV and Delta(S)=0.73 meV are obtained; (3) N(S)(0)/N(0)=11%-20%; (4) the observation of the kink in gamma(H) curve suggests that the two-gap scenario is more favorable than the anisotropic s-wave model to describe the gap structure of NbSe(2); and (5) Delta(S) is more isotropic and has a three-dimensional-like feature and is located either on the Se or the bonding Nb Fermi sheets.
URI: http://dx.doi.org/10.1103/PhysRevB.76.212504
ISSN: 1098-0121
DOI: 10.1103/PhysRevB.76.212504
Volume: 76
Issue: 21
Begin Page: 
End Page: 
Appears in Collections:Articles