TY - JOUR
T1 - Topological insulators and nematic phases from spontaneous symmetry breaking in 2D fermi systems with a quadratic band crossing
AU - Sun, Kai
AU - Yao, Hong
AU - Fradkin, Eduardo
AU - Kivelson, Steven A.
PY - 2009/8/6
Y1 - 2009/8/6
N2 - 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 ±2π 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.
AB - 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 ±2π 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.
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U2 - 10.1103/PhysRevLett.103.046811
DO - 10.1103/PhysRevLett.103.046811
M3 - Article
C2 - 19659389
AN - SCOPUS:68849089683
VL - 103
JO - Physical Review Letters
JF - Physical Review Letters
SN - 0031-9007
IS - 4
M1 - 046811
ER -