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arXiv · 2109.06059

Quantum Criticality of Anti-ferromagnetism and Superconductivity with Relativity

Hanqing Liu·Emilie Huffman·Shailesh Chandrasekharan·Ribhu K. Kaul
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Abstract

We study a quantum phase transition from a massless to massive Dirac fermion phase in a new two-dimensional bipartite lattice model of electrons that is amenable to sign-free quantum Monte Carlo simulations. Importantly, interactions in our model are not only invariant under $\SU(2)$ symmetries of spin and charge like the Hubbard model, but they also preserve an Ising like electron spin-charge flip symmetry. From unbiased fermion bag Monte Carlo simulations with up to 2304 sites, we show that the massive fermion phase spontaneously breaks this Ising symmetry, picking either anti-ferromagnetism or superconductivity and that the transition at which both orders are simultaneously quantum critical, belongs to a new "chiral spin-charge symmetric" universality class. We explain our observations using effective potential and renormalization group calculations within the framework of a continuum field theory.

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Hanqing Liu, Emilie Huffman, Shailesh Chandrasekharan, Ribhu K. Kaul. 2022-12-22. Quantum Criticality of Anti-ferromagnetism and Superconductivity with Relativity. https://doi.org/10.1103/physrevlett.128.117202

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