Nernst response, viscosity and mobile entropy in vortex liquids

Abstract

In a liquid of superconducting vortices, a longitudinal thermal gradient generates a transverse electric field. This Nernst signal peaks at an intermediate temperature and magnetic field, presumably where the entropy difference between the vortex core and the superfluid environment is largest. There is a puzzling similarity of the amplitude of this peak across many different superconductors. This peak can be assimilated to a minimum in the viscosity to entropy density ratio of the vortex liquid. Expressed in units of $\frac{\hslash }{k_B}$, this minimum is one order of magnitude larger than what is seen in common liquids. Moreover, the entropy stocked in the vortex core is \textit{not} identical to the entropy bound to a moving magnetic flux line. Due to a steady exchange of normal quasi-particles, entropy can leak from the vortex core. A slowly moving vortex will be peeled off its entropy within a distance of the order of a superconducting coherence length, provided that the $\frac{\Delta }{E_F}$ ratio is sufficiently large.

17 pages, 5 figures

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Cited by in corpus (4)

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• Nernst effect and its thickness dependence in superconducting NbN films
• Study on fluctuations of interface-enhanced superconductivity in ultrathin FeSe/SrTiO3 by the Nernst effect
• Nernst Sign-Reversal in the Hexatic Vortex Phase of Weakly Disordered a-MoGe Thin Films