title: Fractional topological phases and broken time-reversal symmetry in strained graphene.
abstract: We show that strained or deformed honeycomb lattices are promising platforms to realize fractional topological quantum states in the absence of any magnetic field. The strain-induced pseudomagnetic fields are oppositely oriented in the two valleys and can be as large as 60-300 T as reported in recent experiments. For strained graphene at neutrality, a spin- or a valley-polarized state is predicted depending on the value of the on-site Coulomb interaction. At fractional filling, the unscreened Coulomb interaction leads to a valley-polarized fractional quantum Hall liquid which spontaneously breaks time-reversal symmetry. Motivated by artificial graphene systems, we consider tuning the short-range part of interactions and demonstrate that exotic valley symmetric states, including a valley fractional topological insulator and a spin triplet superconductor, can be stabilized by such interaction engineering.
authors.affiliation: Department of Physics, University of Illinois, Urbana, Illinois 61801, USA. pouyan@berkeley.edu
authors.forename: Pouyan
authors.initials: P
authors.lastname: Ghaemi
authors.forename: Jérôme
authors.initials: J
authors.lastname: Cayssol
authors.forename: D N
authors.initials: DN
authors.lastname: Sheng
authors.forename: Ashvin
authors.initials: A
authors.lastname: Vishwanath