Metal to insulator transition on the N = 0 Landau level in graphene

TL;DR

This study investigates the temperature-dependent magnetotransport properties of single-layer graphene under high magnetic fields, revealing a metal-insulator transition near a specific filling factor and proposing a universal phase diagram for this quantum transition.

Contribution

It provides the first detailed experimental analysis of the metal-insulator transition in graphene's N=0 Landau level and introduces a universal phase diagram for this quantum phase transition.

Findings

Metal-insulator transition occurs at filling factor ~0.65.

Critical resistivity is approximately R_K/2.

Transition correlates with zero plateau in Hall conductivity.

Abstract

The magnetotransport in single layer graphene has been experimentally investigated in magnetic fields up to 18 T as a function of temperature. A pronounced T-dependence is observed for T < 50 K, which is either metallic, or insulating, depending on the filling factor nu. The metal-insulator transition (MIT) occurs at nu_c ~ 0.65 and in the regime of the dissipative transport, where the longitudinal resistance Rxx > R_K/2. The critical resistivity (Rxx per square) is rho_xx(nu_c) ~ R_K/2 and is correlated with the appearance of zero plateau in Hall conductivity sigma_xy(nu) and peaks in sigma_xx(nu). This leads us to construct a universal low-T (n, B) phase diagram of this quantum phase transition.