Emergence of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>p</mml:mi><mml:mo>+</mml:mo><mml:mi>i</mml:mi><mml:mi>p</mml:mi></mml:mrow></mml:math> superconductivity in two-dimensional doped Dirac systems
Zheng‐Cheng Gu, Hong‐Chen Jiang, G. Baskaran
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 $(\ensuremath{\delta}<0.2)$, 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.