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

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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Cited by in corpus (2)

• Impact of $e-e$ interactions on the superfluid density of dirty superconductors
• Nonintrinsic origin of the magnetic-field-induced metal-insulator and electronic phase transitions in graphite