The Nernst response of mobile superconducting vortices, Kamran Behnia ESPCI/CNRS
seminaire hebdomadaire SMQ
Any solid hosting mobile charge carriers will produce an electric field in presence of a thermal gradient. This is a consequence of the combined conservation of energy and particle number. The Nernst effect refers to the off-diagonal component of this thermoelectric response emerging in presence of a finite magnetic field.
At the beginning of the present century, it was generally assumed that the quasi-particle contribution to the Nernst signal is negligible and a BCS superconductor cannot produce a Nernst signal far above its critical temperature. These assumptions were contradicted by subsequent experiments, which showed that the transverse thermoelectric response quantifies the amount of entropy bound to a mobile carrier of magnetic flux .
A recent surprise  is that the entropy carried by a mobile superconducting vortex is much smaller than what it stocks in its core. Available experimental data point to the universality of the mobile sheet entropy of a magnetic flux line across different superconductors with vastly different critical temperatures. This may be due to an information barrier surrounding the topological singularity of vortices in fermionic superfluids .
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