Nernst response, viscosity and mobile entropy in vortex liquids
1Laboratoire de Physique et Etude des Matériaux (CNRS- Sorbonne Université), ESPCI Paris, PSL University, 75005 Paris, France.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|December 21, 2022
Summary
A thermal gradient in superconducting vortices creates a transverse electric field, a Nernst signal. This signal
Area of Science:
- Condensed matter physics
- Superconductivity research
Background:
- Superconducting vortices exhibit complex behavior under thermal gradients.
- The Nernst effect in vortex liquids is not fully understood.
- Entropy dynamics within vortex cores are crucial for understanding their properties.
Purpose of the Study:
- To investigate the generation of transverse electric fields (Nernst signal) in a liquid of superconducting vortices.
- To understand the peak behavior of the Nernst signal in relation to temperature and magnetic field.
- To explore the relationship between vortex core entropy, viscosity, and superfluid environment.
Main Methods:
- Applying a longitudinal thermal gradient to a superconducting vortex liquid.
- Measuring the transverse electric field (Nernst signal) generated.
- Analyzing the Nernst signal's dependence on temperature and magnetic field.
- Investigating the viscosity to entropy density ratio of the vortex liquid.
Main Results:
- A transverse electric field (Nernst signal) is generated by a longitudinal thermal gradient in superconducting vortices.
- The Nernst signal exhibits a peak at intermediate temperatures and magnetic fields.
- A puzzling similarity in peak amplitude across different superconductors was observed.
- The vortex core entropy differs from entropy bound to moving flux lines due to quasi-particle exchange.
Conclusions:
- The Nernst signal peak is linked to the maximum entropy difference between vortex cores and the superfluid.
- The observed minimum in viscosity to entropy density ratio is significantly larger than in common liquids.
- Entropy can leak from vortex cores via normal quasi-particles, affecting their properties.
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