Emergence of p+ip superconductivity in two-dimensional doped Dirac systems

Abstract

Searching for the p+ip superconducting (SC) state has become a fascinating subject in condensed matter physics recently, as a dream application awaiting in topological quantum computation. Unfortunately, so far there is no universal principle for realizing p+ip in generic solid-state systems. Here we report a theoretical discovery of a p+ip SC ground state (coexisting with ferromagnetic order) in the honeycomb lattice Hubbard model in the extremely strong-coupling limit (e.g., infinite U) at low doping (δ<0.2), by using both the state-of-art Grassmann tensor product state approach and a continuum quantum field theory approach. Our discovery suggests a mechanism for the p+ip SC state in generic strongly correlated systems based on spin-charge separation and the charge current–current coupling scenario, which opens a door towards experimental realization. The p+ip SC state has an instability towards a potential non-Fermi liquid with a large but finite U. Nevertheless, by applying an in-plane Zeeman field, such a p+ip SC state can be stabilized with finite U in a very wide range of doping. Relevant realistic materials are also proposed.

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