Two-dimensional mixture of dipolar fermions: Equation of state and magnetic phases

Tommaso Comparin, Raúl Bombín, Markus Holzmann, Ferran Mazzanti, Jordi Boronat, and Stefano Giorgini
Phys. Rev. A 99, 043609 – Published 8 April 2019

Abstract

We study a two-component mixture of fermionic dipoles in two dimensions at zero temperature, interacting via a purely repulsive 1/r3 potential. This model can be realized with ultracold atoms or molecules when their dipole moments are aligned in the confinement direction orthogonal to the plane. We characterize the unpolarized mixture by means of the diffusion Monte Carlo technique. Computing the equation of state, we identify the regime of validity for a mean-field theory based on a low-density expansion and compare our results with the hard-disk model of repulsive fermions. At high density, we address the possibility of itinerant ferromagnetism, namely, whether the ground state can be fully polarized in the fluid phase. Within the fixed-node approximation, we show that the accuracy of Jastrow-Slater trial wave functions, even with the typical two-body backflow correction, is not sufficient to resolve the relevant energy differences. By making use of the iterative-backflow improved trial wave functions, we observe no signature of a fully polarized ground state up to the freezing density.

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  • Received 20 December 2018

DOI:https://doi.org/10.1103/PhysRevA.99.043609

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Tommaso Comparin1,*, Raúl Bombín2,1, Markus Holzmann3,4, Ferran Mazzanti2, Jordi Boronat2, and Stefano Giorgini1

  • 1INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Trento, Italy
  • 2Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034, Barcelona, Spain
  • 3Univ. Grenoble Alpes, CNRS, LPMMC, 3800 Grenoble, France
  • 4Institut Laue-Langevin, BP 156, F-38042 Grenoble Cedex 9, France

  • *tommaso.comparin@unitn.it

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Vol. 99, Iss. 4 — April 2019

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