  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.
