Interaction-driven Lifshitz transition with dipolar fermions in optical lattices

TL;DR

This paper demonstrates that anisotropic dipole-dipole interactions in ultracold fermionic atoms can induce a topological Lifshitz transition, controllable via dipole orientation, affecting Fermi surface topology and related physical properties.

Contribution

It reveals an interaction-driven Lifshitz transition in ultracold dipolar fermions, showing how dipole orientation tuning can control topological changes in the Fermi surface.

Findings

Fermi surface deformation due to dipolar interactions

Observation of a topological Lifshitz transition

Impact on density correlations and excitation spectrum

Abstract

Anisotropic dipole-dipole interactions between ultracold dipolar fermions break the symmetry of the Fermi surface and thereby deform it. Here we demonstrate that such a Fermi surface deformation induces a topological phase transition -- so-called Lifshitz transition -- in the regime accessible to present-day experiments. We describe the impact of the Lifshitz transition on observable quantities such as the Fermi surface topology, the density-density correlation function, and the excitation spectrum of the system. The Lifshitz transition in ultracold atoms can be controlled by tuning the dipole orientation and -- in contrast to the transition studied in crystalline solids -- is completely interaction-driven.