Possible Excitonic Phase of Graphite in the Quantum Limit State

TL;DR

This study investigates graphite under high magnetic fields, revealing a transition near 53 T that suggests the possible formation of an excitonic BCS-like state, characterized by a gapped out-of-plane conduction.

Contribution

It provides experimental evidence for a quantum limit state in graphite and proposes excitonic pairing as a novel explanation for the observed phenomena.

Findings

Hall resistivity approaches zero at 53 T

Anomaly in differential magnetization at 53 T

Transition insensitive to disorder, reduced by hole doping

Abstract

The in-plane resistivity, Hall resistivity and magnetization of graphite were investigated in pulsed magnetic fields applied along the \textit{c}-axis. The Hall resistivity approaches zero at around 53 T where the in-plane and out-of-plane resistivities steeply decrease. The differential magnetization also shows an anomaly at around this field with a similar amplitude compared to that of de Haas-van Alphen oscillations at lower fields. This transition field appears insensitive to disorder, but reduces with doping holes. These results suggest the realization of the quantum limit states above 53 T. As a plausible explanation for the observed gapped out-of-plane conduction above 53 T, the emergence of the excitonic BCS-like state in graphite is proposed.