Low-field magnetotransport in graphene cavity devices

TL;DR

This study investigates how confinement in graphene nanostructures affects low-temperature magnetotransport, revealing increased intravalley scattering near the Dirac point and Coulomb interaction-driven dephasing.

Contribution

It provides new insights into the role of edge disorder and charge inhomogeneities in graphene cavities and their impact on carrier scattering and dephasing mechanisms.

Findings

Intravalley scattering dominates near the Dirac point in graphene cavities.

Dephasing rate follows a parabolic temperature dependence.

Confinement significantly influences carrier transport properties.

Abstract

Confinement and edge structures are known to play significant roles in electronic and transport properties of two-dimensional materials. Here, we report on low-temperature magnetotransport measurements of lithographically patterned graphene cavity nanodevices. It is found that the evolution of the low-field magnetoconductance characteristics with varying carrier density exhibits different behaviors in graphene cavity and bulk graphene devices. In the graphene cavity devices, we have observed that intravalley scattering becomes dominant as the Fermi level gets close to the Dirac point. We associate this enhanced intravalley scattering to the effect of charge inhomogeneities and edge disorder in the confined graphene nanostructures. We have also observed that the dephasing rate of carriers in the cavity devices follows a parabolic temperature dependence, indicating that the direct Coulomb interaction scattering mechanism governs the dephasing at low temperatures. Our results demonstrate the importance of confinement in carrier transport in graphene nanostructure devices.