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Title: Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in 2D Fermi Systems with a Quadratic Band Crossing

Abstract

We investigate the stability of a quadratic band-crossing point (QBCP) in 2D fermionic systems. At the noninteracting level, we show that a QBCP exists and is topologically stable for a Berry flux +-2pi if the point symmetry group has either fourfold or sixfold rotational symmetries. This putative topologically stable free-fermion QBCP is marginally unstable to arbitrarily weak short-range repulsive interactions. We consider both spinless and spin-1/2 fermions. Four possible ordered states result: a quantum anomalous Hall phase, a quantum spin Hall phase, a nematic phase, and a nematic-spin-nematic phase.

Authors:
;  [1]; ;  [2]
  1. Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080 (United States)
  2. Department of Physics, Stanford University, Stanford, California 94305 (United States)
Publication Date:
OSTI Identifier:
21347093
Resource Type:
Journal Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 103; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevLett.103.046811; (c) 2009 The American Physical Society; Journal ID: ISSN 0031-9007
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; FERMIONS; INTERACTIONS; SPIN; STABILITY; SYMMETRY; SYMMETRY BREAKING; SYMMETRY GROUPS; TOPOLOGY; ANGULAR MOMENTUM; MATHEMATICS; PARTICLE PROPERTIES

Citation Formats

Kai, Sun, Fradkin, Eduardo, Hong, Yao, and Kivelson, Steven A. Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in 2D Fermi Systems with a Quadratic Band Crossing. United States: N. p., 2009. Web. doi:10.1103/PHYSREVLETT.103.046811.
Kai, Sun, Fradkin, Eduardo, Hong, Yao, & Kivelson, Steven A. Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in 2D Fermi Systems with a Quadratic Band Crossing. United States. doi:10.1103/PHYSREVLETT.103.046811.
Kai, Sun, Fradkin, Eduardo, Hong, Yao, and Kivelson, Steven A. Fri . "Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in 2D Fermi Systems with a Quadratic Band Crossing". United States. doi:10.1103/PHYSREVLETT.103.046811.
@article{osti_21347093,
title = {Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in 2D Fermi Systems with a Quadratic Band Crossing},
author = {Kai, Sun and Fradkin, Eduardo and Hong, Yao and Kivelson, Steven A},
abstractNote = {We investigate the stability of a quadratic band-crossing point (QBCP) in 2D fermionic systems. At the noninteracting level, we show that a QBCP exists and is topologically stable for a Berry flux +-2pi if the point symmetry group has either fourfold or sixfold rotational symmetries. This putative topologically stable free-fermion QBCP is marginally unstable to arbitrarily weak short-range repulsive interactions. We consider both spinless and spin-1/2 fermions. Four possible ordered states result: a quantum anomalous Hall phase, a quantum spin Hall phase, a nematic phase, and a nematic-spin-nematic phase.},
doi = {10.1103/PHYSREVLETT.103.046811},
journal = {Physical Review Letters},
issn = {0031-9007},
number = 4,
volume = 103,
place = {United States},
year = {2009},
month = {7}
}