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

Year: 2019

Authors: Comparin T., Bombin R., Holzmann M., Mazzanti F., Boronat J., Giorgini S.

Autors Affiliation: Univ Trento, INO CNR BEC Ctr, I-38123 Trento, Italy; Univ Trento, Dipartimento Fis, I-38123 Trento, Italy; Univ Politecn Cataluna, Dept Fis, Campus Nord B4-B5, E-08034 Barcelona, Spain; Univ Grenoble Alpes, LPMMC, CNRS, F-3800 Grenoble, France; Inst Laue Langevin, BP 156, F-38042 Grenoble 9, France.

Abstract: We study a two-component mixture of fermionic dipoles in two dimensions at zero temperature, interacting via a purely repulsive 1/r(3) 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.

Journal/Review: PHYSICAL REVIEW A

Volume: 99 (4)      Pages from: 43609-1  to: 43609-11

More Information: We acknowledge Luca Parisi for useful discussions and Gianluca Bertaina for comments and for providing the data from Ref. [68]. This work has been supported by the Provincia Autonoma di Trento and by the Ministerio de Economia, Industria y Competitividad (ES) under Grant No. FIS201784114-C2-1-P and FPI fellowship BES2015-074088. T.C. thanks the Institute for Nuclear Theory (University of Washington) for hospitality.
KeyWords: Quantum Monte-carlo; Bose-einstein Condensation; Ground-state; Ferromagnetism; Progress; Gas; Molecules; Droplets
DOI: 10.1103/PhysRevA.99.043609

Citations: 7
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