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Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in

Journal Article · · Submitted to Physical Review Letters
OSTI ID:981390

We investigate the stability of a quadratic band-crossing point (QBCP) in 2D fermionic systems. At the non-interacting level, we show that a QBCP exists and is topologically stable for a Berry flux {-+}2{pi}, 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 shortrange 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.

Research Organization:
SLAC National Accelerator Laboratory (SLAC)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC02-76SF00515
OSTI ID:
981390
Report Number(s):
SLAC-PUB-14078
Journal Information:
Submitted to Physical Review Letters, Journal Name: Submitted to Physical Review Letters
Country of Publication:
United States
Language:
English

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