V. Chua and G. A. Fiete, “Exactly Solvable Topological Spin Liquid

1. CAREER: First Exactly Solvable Topological Quantum Spin Liquid with Random ExchangeGregory A. Fiete, University of Texas at Austin, DMR 0955778 Intellectual Merit: A vibrant research area in condensed matter physics is the study of topological phases. The quantum Hall effect and topological insulators are well-known examples, but spin systems on a lattice can also possess topological phases. A long-standing problem is to study disorder in an interacting quantum many-body system. In this work, we study an exactly solvable, disordered, interacting quantum many-body system with topological phases. We show that under a variety of conditions disorder can drive a non-topological phase into a topological one. Local thermal current density profiles of a disordered quasi-one-dimensional “spin wire” (running right to left) for typical disorder realizations possessing chiral edge modes at large disorder: (a) Topological State (b) Non-topological state. V. Chua and G. A. Fiete, “Exactly Solvable Topological Spin Liquid with Random Exchange”. Phys. Rev. B 84, 195129 (2011).

2. CAREER: Exactly Solvable Spin Model with Plethora of PhasesGregory A. Fiete, University of Texas at Austin, DMR 0955778 Broader Impacts: Undergraduate advisee Seth Whitsitt received NSF GRF. Will pursue physics PhD at Harvard. Also named APS LeRoy Apker Award finalist based on his research (see left). Graduate student Rex Lundgren received NSF GRF. PI also supervised “Minority Bridge” undergraduate from smaller Texas institution to bring more underrepresented minorities into physics. Please insert an image (.JPEG) or group of images here to illustrate your broader impacts activities. If you need more space, you may reduce the adjacent textbox. Please use lettering that is clearly visible (i.e. not too small). Please include a brief figure caption. Phase diagram of an exactly solvable gamma matrix spin model on the decorated honeycomb lattice. Gapless phases with a Fermi surface (FS), and gapped phases with Chern numbers are found. S. Whitsitt, V. Chua, G.A. Fiete, arXiv:1204.2803 (To appear in a special edition of The New Journal of Physics.) The PI was invited to address the National Academy of Sciences on the topic of “New Device Applications from Topological Phases”: http://sites.nationalacademies.org/BPA/BPA_067816