https://doi.org/10.1140/epjb/s10051-022-00395-w
Regular Article – Solid State and Materials
Functional renormalization of spinless triangular-lattice fermions: N-patch vs. truncated-unity scheme
1
Institute for Theoretical Physics, University of Cologne, 50937, Cologne, Germany
2
Institute for Theoretical Physics, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
3
Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
4
Institute for Theoretical Physics III, Ruhr-University Bochum, 44801, Bochum, Germany
Received:
14
April
2022
Accepted:
5
August
2022
Published online:
20
September
2022
We study competing orders of spinless fermions in the triangular-lattice Hubbard model with nearest-neighbor interaction. We calculate the effective, momentum-resolved two-particle vertex in an unbiased way in terms of the functional renormalization group method and compare two different schemes for the momentum discretization, one based on dividing the Fermi surface into patches and one based on a channel decomposition. We study attractive and repulsive nearest-neighbor interaction and find a competition of pairing and charge instabilities. In the attractive case, a Pomeranchuk instability occurs at Van Hove filling and f-wave and p-wave pairing emerge when the filling is reduced. In the repulsive case, we obtain a charge density wave at Van Hove filling and extended p-wave pairing with reduced filling. The p-wave pairing solution is doubly degenerate and can realize chiral 
superconductivity with different Chern numbers in the ground state. We discuss implications for strongly correlated spin-orbit coupled hexagonal electron systems such as moiré heterostructures.
© The Author(s) 2022
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