Skyrmion Superfluidity in Two-Dimensional Interacting Fermionic Systems

TL;DR

This paper introduces a novel skyrmion superfluid phase in a two-dimensional fermionic lattice model, characterized by a non-linear sigma model and Maxwell-BF theory, with potential experimental signatures.

Contribution

It develops a new theoretical framework for skyrmion superfluidity in fermionic systems using functional fermionization and effective field theories.

Findings

Identification of a parity-preserving skyrmion superfluid phase

Derivation of a double skyrmion non-linear sigma model

Establishment of measurable signatures in lattice models

Abstract

In this article we describe a multi-layered honeycomb lattice model of interacting fermions which supports a new kind of parity-preserving skyrmion superfluidity. We derive the low-energy field theory describing a non-BCS fermionic superfluid phase by means of functional fermionization. Such effective theory is a new kind of non-linear sigma model, which we call double skyrmion model. In the bi-layer case, the quasiparticles of the system (skyrmions) have bosonic statistics and replace the Cooper-pairs role. Moreover, we show that the model is also equivalent to a Maxwell-BF theory, which naturally establishes an effective Meissner effect without requiring a breaking of the gauge symmetry. Finally, we map effective superfluidity effects to identities among fermionic observables for the lattice model. This provides a signature of our theoretical skyrmion superfluidy that can be detected in a possible implementation of the lattice model in a real quantum system.