Taming the magnetoresistance anomaly in graphite

TL;DR

This paper investigates the magnetoresistance anomaly in graphite, demonstrating control over the high-resistance state through charge carrier modulation and revealing its complex dependence on in-plane effects, carrier type, and sample thickness.

Contribution

It experimentally modulates the high-resistance state in graphite via charge neutrality level control, challenging existing theories about its origin.

Findings

HRS can be triggered by both electrons and holes

HRS is attenuated near the charge neutrality level

Sample thickness influences the HRS behavior

Abstract

At low temperatures, graphite presents a magnetoresistance anomaly which manifests as a transition to a high-resistance state (HRS) above a certain critical magnetic field $\text{B}_\text{c}$. Such HRS is currently attributed to a c-axis charge-density-wave taking place only when the lowest Landau level is populated. By controlling the charge carrier concentration of a gated sample through its charge neutrality level (CNL), we were able to experimentally modulate the HRS in graphite for the first time. We demonstrate that the HRS is triggered both when electrons and holes are the majority carriers but is attenuated near the CNL. Taking screening into account, our results indicate that the HRS possess a strong in-plane component and can occur below the quantum limit, being at odds with the current understanding of the phenomenon. We also report the effect of sample thickness on the HRS.