https://doi.org/10.1140/epjb/s10051-022-00472-0
Regular Article - Solid State and Materials
Spectrum, Lifshitz transitions and orbital current in frustrated fermionic ladders with a uniform flux
1
The Andronikashvili Institute of Physics, 0177, Tbilisi, Georgia
2
Ilia State University, 0162, Tbilisi, Georgia
3
The Abdus Salam International Centre for Theoretical Physics, 34151, Trieste, Italy
Received:
1
November
2022
Accepted:
16
December
2022
Published online:
3
January
2023
Ultracold Fermi gases with synthetic gauge field represent an excellent platform to study the combined effect of lattice frustration and an effective magnetic flux close to one flux quantum per particle. The minimal theoretical model to accomplish this task is a system of spinless noninteracting fermions on a triangular two-chain flux ladder. In this paper we consider this model close to half-filling, with interchain hopping amplitudes alternating along the zigzag bonds of the ladder and being small. In such setting qualitative changes in the ground state properties of the model, most notably the flux-induced topological Lifshitz transitions are shifted towards the values of the flux per a diatomic plaquette (f) close to the flux quantum (
). Geometrical frustration of the lattice breaks the 
particle-hole spectral symmetry present in non-frustrated ladders, and leads to splitting of the degeneracies at metal–insulator transitions. A remarkable feature of a translationally invariant triangular ladder is the appearance of isolated Dirac node at the Brillouin zone boundary, rendering the ground state at 
semi-metallic. We calculate the flux dependence of the orbital current and identify Lifshitz critical points by the singularities in this dependence at a constant chemical potential 
and constant particle density 
. The absence of the particle-hole symmetry in the triangular ladder leads to the asymmetry between particle (
) and hole (
) doping and to qualitatively different results for the phase diagram, Lifshitz points and the flux dependence of the orbital current in the settings 
and 
.
Copyright comment Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
