Infrared probe of the anomalous magnetotransport of highly oriented pyrolytic graphite in the extreme quantum limit

Abstract

We present a systematic investigation of the magnetoreflectance $R(\ensuremath{\omega},B)$ of highly oriented pyrolytic graphite in magnetic field $B$ up to $18\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. From these measurements, we report the determination of lifetimes $\ensuremath{\tau}$ associated with the lowest Landau levels in the quantum limit. We find a linear field dependence for inverse lifetime $1∕\ensuremath{\tau}(B)$ of the lowest Landau levels, which is consistent with the hypothesis of a three-dimensional (3D) to 1D crossover in an anisotropic 3D metal in the quantum limit. This enigmatic result uncovers the origin of the anomalous linear in-plane magnetoresistance observed both in bulk graphite and recently in mesoscopic graphite samples.