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

Flávio L. N. Santos, Mônica A. Caracanhas, M. C. O. Aguiar, and Rodrigo G. Pereira
Phys. Rev. B 101, 155120 – Published 16 April 2020

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.

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  • Received 31 December 2019
  • Revised 18 March 2020
  • Accepted 19 March 2020

DOI:https://doi.org/10.1103/PhysRevB.101.155120

©2020 American Physical Society

Physics Subject Headings (PhySH)

Atomic, Molecular & OpticalCondensed Matter, Materials & Applied Physics

Authors & Affiliations

Flávio L. N. Santos1,2, Mônica A. Caracanhas3, M. C. O. Aguiar1,2, and Rodrigo G. Pereira4

  • 1Departamento de Física, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, Minas Gerais 30123-970, Brazil
  • 2Université Paris-Saclay, CNRS, Laboratoire de Physiques des Solides, 91405 Orsay, France
  • 3Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo 13560-970, Brazil
  • 4International Institute of Physics and Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte 59078-970, Brazil

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Issue

Vol. 101, Iss. 15 — 15 April 2020

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