Intrinsic Superconductivity at 25 K in Highly Oriented Pyrolytic Graphite

TL;DR

This study reports intrinsic superconductivity at 25 K in highly oriented pyrolytic graphite, revealing non-homogeneous superconducting domains with unique magnetic and electronic properties.

Contribution

It provides evidence of intrinsic superconductivity in graphite and discusses a potential interior-gap mechanism involving different electronic masses.

Findings

Superconductivity observed at ~25 K in graphite.

Presence of Josephson-like resistance hysteresis.

Absence of Shubnikov-de Haas oscillations.

Abstract

High resolution magnetoresistance data in highly oriented pyrolytic graphite thin samples manifest non-homogenous superconductivity with critical temperature $T_c \sim 25 $K. These data exhibit: i) hysteretic loops of resistance versus magnetic field similar to Josephson-coupled grains, ii) quantum Andreev's resonances and iii) absence of the Schubnikov-de Haas oscillations. The results indicate that graphite is a system with non-percolative superconducting domains immersed in a semiconducting-like matrix. As possible origin of the superconductivity in graphite we discuss interior-gap superconductivity when two very different electronic masses are present.