# Field-induced insulating states in a graphene superlattice

## TL;DR

This study explores magnetic field-induced insulating states in a graphene superlattice, revealing new quantum Hall phenomena and characterizing the energy gaps and microscopic origins of emergent gapped Dirac quasiparticles.

## Contribution

It provides the first detailed experimental investigation of field-induced insulating states in a graphene/h-BN superlattice near the Hofstadter spectrum.

## Key findings

- Identification of insulating states at specific flux quanta
- Quantification of energy gaps from temperature-dependent resistance
- Determination of the dispersion of gapped Dirac quasiparticles

## Abstract

We report on high-field magnetotransport (B up to 35 T) on a gated superlattice based on single-layer graphene aligned on top of hexagonal boron nitride. The large-period moir\'e modulation (15 nm) enables us to access the Hofstadter spectrum in the vicinity of and above one flux quantum per superlattice unit cell (Phi/Phi_0 = 1 at B = 22 T). We thereby reveal, in addition to the spin-valley antiferromagnet at nu = 0, two insulating states developing in positive and negative effective magnetic fields from the main nu = 1 and nu = -2 quantum Hall states respectively. We investigate the field dependence of the energy gaps associated with these insulating states, which we quantify from the temperature-activated peak resistance. Referring to a simple model of local Landau quantization of third generation Dirac fermions arising at Phi/Phi_0 = 1, we describe the different microscopic origins of the insulating states and experimentally determine the energy-momentum dispersion of the emergent gapped Dirac quasi-particles.