Helical quantum Hall phase in graphene on SrTiO3
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 insulating state is observed that 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 through a suitable screening of the Coulomb interaction with the high dielectric constant of a strontium titanate (SrTiO3) substrate. Robust helical edge transport emerged at magnetic fields as low as 1 tesla and withstanding temperatures up to 110 kelvin over micron-long distances. This versatile graphene platform may find applications in spintronics and topological quantum computation.
- Publication:
-
Science
- Pub Date:
- February 2020
- DOI:
- 10.1126/science.aax8201
- arXiv:
- arXiv:1907.02299
- Bibcode:
- 2020Sci...367..781V
- Keywords:
-
- PHYSICS;
- Condensed Matter - Mesoscale and Nanoscale Physics
- E-Print:
- Main text + SI