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Thermal signatures of Little-Parks effect in the heat capacity of mesoscopic superconducting rings

Florian R. Ong·Olivier Bourgeois·Sergey E. Skipetrov·Jacques Chaussy
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Abstract

We present the first measurements of thermal signatures of the Little-Parks effect using a highly sensitive nanocalorimeter. Small variations of the heat capacity $C\_p$ of 2.5 millions of non interacting micrometer-sized superconducting rings threaded by a magnetic flux $Φ$ have been measured by attojoule calorimetry. This non-invasive method allows the measurement of thermodynamic properties -- and hence the probing of the energy levels -- of nanosystems without perturbing them electrically. It is observed that $C\_p$ is strongly influenced by the fluxoid quantization (Little-Parks effect) near the critical temperature $T\_c$. The jump of $C\_p$ at the superconducting phase transition is an oscillating function of $Φ$ with a period $Φ\_0=h/2e$, the magnetic flux quantum, which is in agreement with the Ginzburg-Landau theory of superconductivity.

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Florian R. Ong, Olivier Bourgeois, Sergey E. Skipetrov, Jacques Chaussy. 2006-09-21. Thermal signatures of Little-Parks effect in the heat capacity of mesoscopic superconducting rings. https://doi.org/10.1103/physrevb.74.140503

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