Superconducting fluctuations observed far above T$_\mathrm{c}$ in the isotropic superconductor K$_3$C$_{60}$

• URL: http://arxiv.org/abs/2109.08679v1
• Date: Fri, 17 Sep 2021 17:59:01 GMT
• Title: Superconducting fluctuations observed far above T$_\mathrm{c}$ in the isotropic superconductor K$_3$C$_{60}$
• Authors: Gregor Jotzu, Guido Meier, Alice Cantaluppi, Andrea Cavalleri, Daniele Pontiroli, Mauro Ricc\`o, Arzhang Ardavan, Moon-Sun Nam
• Abstract summary: We report on the observation of a sizeable magneto-thermoelectric (Nernst) effect in the normal state of K$_3$C$_60$. The anomalous Nernst effect emerges from an ordinary quasiparticle background below a temperature of 80K, far above T$_textc$ = 20K.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Alkali-doped fullerides are strongly correlated organic superconductors that exhibit high transition temperatures, exceptionally large critical magnetic fields and a number of other unusual properties. The proximity to a Mott insulating phase is thought to be a crucial ingredient of the underlying physics, and may also affect precursors of superconductivity in the normal state above T$_\text{c}$. We report on the observation of a sizeable magneto-thermoelectric (Nernst) effect in the normal state of K$_3$C$_{60}$, which displays the characteristics of superconducting fluctuations. The anomalous Nernst effect emerges from an ordinary quasiparticle background below a temperature of 80K, far above T$_\text{c}$ = 20K. At the lowest fields and close to T$_\text{c}$, the scaling of the effect is captured by a model based on Gaussian fluctuations. The temperature up to which we observe fluctuations is exceptionally high for a three-dimensional isotropic system, where fluctuation effects are usually suppressed.

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