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arXiv · 1804.00179

Superconducting Sweet-Spot in Microcrystalline Graphite Revealed by Point-Contact Spectroscopy

Frank Arnold·Jan Nyeki·John Saunders
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Abstract

In this letter we describe the observation of a magnetic field dependent electronic gap, suggestive of local superconductivity, in the point-contact spectrum of micro-crystalline graphite. Magnetic field dependent point-contact spectroscopy was carried out at a temperature of $1.8\,\mathrm{K}$ using an etched aluminium tip. At zero field a gap structure in the differential conductance is observed, showing a gap of $\Delta = 4.2\,\mathrm{meV}$. On applying magnetic fields of up to $500\,\mathrm{mT}$, this gap gradually closes, following the theoretical prediction by Ginzburg and Landau for a fully flux-penetrated superconductor. By applying BCS-theory, we infer a critical superconducting temperature of $14\,\mathrm{K}$.

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Frank Arnold, Jan Nyeki, John Saunders. 2018-03-31. Superconducting Sweet-Spot in Microcrystalline Graphite Revealed by Point-Contact Spectroscopy. https://doi.org/10.1134/s0021364018090023

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