Low Field Anomaly in the Specific Heat of <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="italic">s</mi></math></span>-Wave Superconductors due to the Expansion of the Vortex Cores

J. E. Sonier; M. F. Hundley; J. D. Thompson; J. W. Brill

doi:10.1103/PhysRevLett.82.4914

Low Field Anomaly in the Specific Heat of $s$ -Wave Superconductors due to the Expansion of the Vortex Cores

J. E. Sonier, M. F. Hundley, J. D. Thompson, and J. W. Brill

Phys. Rev. Lett. 82, 4914 – Published 14 June 1999

Abstract

The magnetic field dependence of the electronic specific heat $C (H)$ in the $s$ -wave superconductor ${NbSe}_{2}$ shows curvature at low fields, resembling the near $\sqrt{H}$ term in $C (H)$ which has been reported in high- $T_{c}$ superconductors and attributed to a $d_{x^{2} {- y}^{2}}$ -wave pairing state. In ${NbSe}_{2}$ we find that the low field behavior in $C (H)$ is described quantitatively by the expansion of vortex cores and the field dependence of the magnetic induction $B$ above $H_{c 1}$ . The associated change in the density of quasiparticle states localized in the vortex cores provides a simple explanation for the “low field anomaly” in $C (H)$ observed in $s$ -wave superconductors.

Received 10 November 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.4914

Authors & Affiliations

J. E. Sonier¹, M. F. Hundley¹, J. D. Thompson¹, and J. W. Brill²

¹Los Alamos National Laboratory, Los Alamos, New Mexico 87545
²Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055