# Helical quantum Hall phase in graphene on SrTiO$_3$

## TL;DR

This study demonstrates the induction of a helical quantum Hall phase in graphene on SrTiO$_3$, enabling robust edge transport at low magnetic fields and high temperatures, advancing potential applications in spintronics and quantum computing.

## Contribution

We achieved a topological quantum Hall phase in graphene by using SrTiO$_3$ to screen Coulomb interactions, revealing a new platform for topological and spintronic devices.

## Key findings

- Helical edge transport observed at 1 Tesla.
- Edge states withstand temperatures up to 110 K.
- Screening with SrTiO$_3$ enables topological phase in graphene.

## Abstract

The ground state of charge neutral graphene under perpendicular magnetic field was predicted to be a quantum Hall topological insulator with a ferromagnetic order and spin-filtered, helical edge channels. In most experiments, however, an otherwise insulating state is observed and is accounted for by lattice-scale interactions that promote a broken-symmetry state with gapped bulk and edge excitations. We tuned the ground state of the graphene zeroth Landau level to the topological phase via a suitable screening of the Coulomb interaction with a SrTiO$_3$ high-$k$ dielectric substrate. We observed robust helical edge transport emerging at a magnetic field as low as 1 tesla and withstanding temperatures up to 110 kelvins over micron-long distances. This new and versatile graphene platform opens new avenues for spintronics and topological quantum computation.