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arXiv · 1512.07908

Fermion-induced quantum critical points

Zi-Xiang Li·Yi-Fan Jiang·Shao-Kai Jian·Hong Yao
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Abstract

A unified theory of quantum critical points beyond the conventional Landau-Ginzburg-Wilson paradigm remains unknown. According to Landau cubic criterion, phase transitions should be first-order when cubic terms of order parameters are allowed by symmetry in the Landau-Ginzburg free energy. Here, from renormalization group (RG) analysis we show that second-order quantum phase transitions can occur at such putatively first-order transitions in interacting two-dimensional Dirac semimetals. As such type of Landau-forbidden quantum critical points are induced by gapless fermions, we call them fermion-induced quantum critical points (FIQCP). We further introduce a microscopic model of SU(N) fermions on the honeycomb lattice featuring a transition between Dirac semimetals and Kekule valence bond solids. Remarkably, our large-scale sign-problem-free Majorana quantum Monte Carlo simulations show convincing evidences of a FIQCP for N=2,3,4,5,6, consistent with the RG analysis. We finally discuss possible experimental realizations of the FIQCP in graphene and graphene-like materials.

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Zi-Xiang Li, Yi-Fan Jiang, Shao-Kai Jian, Hong Yao. 2015-12-24. Fermion-induced quantum critical points. https://doi.org/10.1038/s41467-017-00167-6

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