Magnetoconductance Oscillations in Electron-hole Hybridization Gaps and Valley Splittings in Tetralayer Graphene

TL;DR

This study reveals valley splitting and unique magnetoconductance oscillations in tetralayer graphene, caused by band inversion and hybridization of Landau levels, advancing understanding of its electronic properties.

Contribution

It uncovers the origin of magnetoconductance oscillations in tetralayer graphene due to electron-hole hybridization and band inversion, which was not previously understood.

Findings

Valley splitting observed only in the light-mass subband.

Unexpected magnetoconductance oscillations in bulk gaps.

Hybridization between electron-like and hole-like Landau levels causes these oscillations.

Abstract

We investigate magnetotransport on Bernal-stacked tetralayer graphene whose band structure consists of two massive subbands with different effective masses. Under a finite displacement field, we observe valley splitting of Landau levels (LLs) only in the light-mass subband, consistent with a tight-binding model. At low density, we find unexpected magnetoconductance oscillations in bulk gaps which originate from a series of hybridizations between electron-like and hole-like LLs due to band inversion in tetralayer graphene. In contrast to a trivial LL quantization gap, these inverted hybridization gaps can lead to a change in number of edge states which explains the observed oscillations.