Magnetothermal Conductivity of Highly Oriented Pyrolytic Graphite in the Quantum Limit

TL;DR

This study investigates how magnetic fields affect the heat conduction in highly oriented pyrolytic graphite at low temperatures, revealing oscillations linked to quantum effects and violations of classical laws.

Contribution

It provides new experimental data on the magnetothermal properties of graphite in the quantum limit, highlighting oscillations and deviations from the Wiedemann-Franz law.

Findings

Large oscillations in thermal conductivity at high magnetic fields.

Observation of quantum Hall effect signatures in thermal transport.

Violation of Wiedemann-Franz law in high-field regime.

Abstract

We report on the magnetic field (0T$ \le B \le 9$T) dependence of the longitudinal thermal conductivity $\kappa(T,B)$ of highly oriented pyrolytic graphite in the temperature range 5 K $\le T\le$ 20 K for fields parallel to the $c-$axis. We show that $\kappa(T,B)$ shows large oscillations in the high-field region (B > 2 T) where clear signs of the Quantum-Hall effect are observed in the Hall resistance. With the measured longitudinal electrical resistivity we show that the Wiedemann-Franz law is violated in the high-field regime.