Bound states in two-dimensional Fermi systems with quadratic band touching

Abstract

The formation of bound states between mobile impurity particles and fermionic atoms has been demonstrated in spin-polarized Fermi gases with attractive interspecies interaction. We investigate bound states of mobile impurities immersed in a two-dimensional system with a symmetry-protected quadratic band touching. In addition to the standard s-wave interaction, we consider an anisotropic dipolar exchange interaction that locally breaks point group symmetries. Using a weak-coupling renormalization group approach and a ladder approximation for the impurity-fermion propagator, we establish that the number of bound states can be controlled by varying the anisotropy of the exchange interaction. Our results show that the degeneracy and momentum dependence of the binding energies reflect some distinctive properties of the quadratic band touching.

arXiv comment9 pages, 8 figures

References in corpus (36)

• The physics of dipolar bosonic quantum gases
• Renormalization Group Approach to Interacting Fermions
• Realizing a lattice spin model with polar molecules
• Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms
• Metastability and Coherence of Repulsive Polarons in a Strongly Interacting Fermi Mixture
• Efimov Physics: a review
• Attractive and repulsive Fermi polarons in two dimensions
• Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in 2D Fermi Systems with a Quadratic Band Crossing
• Polarons, Dressed Molecules, and Itinerant Ferromagnetism in ultracold Fermi gases
• Tunable Superfluidity and Quantum Magnetism with Ultracold Polar Molecules
• Repulsive Fermi polarons in a resonant mixture of ultracold ${}^6$Li atoms
• Bose polarons near quantum criticality
• Topological semimetal in a fermionic optical lattice
• Many-body dynamics of dipolar molecules in an optical lattice
• Fermi polarons in two dimensions
• Trimers, molecules and polarons in imbalanced atomic Fermi gases
• Physics of higher orbital bands in optical lattices: a review
• Polaron-molecule transitions in a two-dimensional Fermi gas
• Interferometric Measurements of Many-body Topological Invariants using Mobile Impurities
• Polarons and Molecules in a Two-Dimensional Fermi Gas
• Renormalization group study of interaction-driven quantum anomalous Hall and quantum spin Hall phases in quadratic band crossing systems
• Nematic, topological and Berry phases when a flat and a parabolic band touch
• Topologically induced avoided band crossing in an optical chequerboard lattice
• Spontaneous symmetry breakings in two-dimensional kagome lattice
• Instabilities of quadratic band crossing points
• The Fermi-polaron in two dimensions: Importance of the two-body bound state
• Dropping an impurity into a Chern insulator: a polaron view on topological matter
• Tunning topological phase and quantum anomalous Hall effect by interaction in quadratic band touching systems
• Quantum Anomalous Hall Insulator Stabilized By Competing Interactions
• Topological polarons, quasiparticle invariants and their detection in 1D symmetry-protected phases
• Frustrated Magnetism of Dipolar Molecules on a Square Optical Lattice: Prediction of a Quantum Paramagnetic Ground State
• Polaron in a $p+ip$ Fermi topological superfluid
• Mobile impurity near the superfluid-Mott insulator quantum critical point in two dimensions
• Tkachenko polarons in vortex lattices
• Emergence of superconductivity in a doped single-valley quadratic band crossing system of spin-1/2 fermions
• Tunable breakdown of the polaron picture for mobile impurities in a topological semimetal