# Condensed-Matter Physics & Materials Science Seminar

## "A model of chiral spin liquids with tunable edge states"

#### Presented by Christopher Mudry, Paul Scherrer Institute, Switzerland

Thursday, June 15, 2017, 1:30 pm — Bldg. 734, ISB Conference Room 201 (upstairs)

We construct a quantum field theory in (2+1)-dimensional spacetime for strongly interacting Majorana fields that is amenable to a mean-field approximation. The mean-field phase diagram predicts the existence of two competing phases, one of which supports chiral non-Abelian topological order, while the other supports chiral Abelian topological order. The two mean-field phases are separated by a continuous phase transition. This quantum field theory captures the low-energy physics of quantum spin-1/2 localized on the sites of a lattice whose interactions are $SU(2)$ symmetric but break time-reversal symmetry. The lattice geometry can be interpreted as a one-dimensional stacking of two-leg ladders or as a bilayer of two square lattices. Both incompressible ground states can thus be thought of as chiral spin liquids in two-dimensional space supporting non-Abelian and Abelian topological order, respectively.

Hosted by: Alexei Tsvelik

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