arXiv:0907.1345 · Physical Review Letters

Ferronematic Ground State of the Dilute Dipolar Fermi Gas

Benjamin M. Fregoso, Eduardo Fradkin

Published Nov 13, 2009• 77 citations

Abstract

It is shown that a homogeneous two-component Fermi gas with (long-range) dipolar and short-range isotropic interactions has a ferronematic phase for suitable values of the dipolar and short-range coupling constants. The ferronematic phase is characterized by having a nonzero magnetization and long-range orientational uniaxial order. The Fermi surface of the spin-up (-down) component is elongated (compressed) along the direction of the magnetization.

DOI: 10.1103/physrevlett.103.205301

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arXiv:0907.1345 · Physical Review Letters

Ferronematic Ground State of the Dilute Dipolar Fermi Gas

Benjamin M. Fregoso, Eduardo Fradkin

Published Nov 13, 2009• 77 citations

arXiv HTML PDF

Abstract

DOI: 10.1103/physrevlett.103.205301

Related papers

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Interacting two-component Fermi gases are at the heart of our understanding of macroscopic quantum phenomena such as superconductivity. The changing nature of the interaction is expected to head to novel quantum phases. Here we study the ground state of a two-component fermionic gas in a harmonic potential with dipolar and contact interactions. Using a variational Wigner function we present the phase diagram of the system with equal but opposite values of the magnetic moment. We identify the second-order phase transition from paramagnetic to ferronematic phases. Moreover, we show the impact of the experimentally relevant magnetic field on the stability and magnetization of the system. We also investigate a two-component Fermi gas with large but almost equal values of the magnetic moment to study how the interplay between contact and dipolar interactions affects the stability properties of the mixture. To be specific we discuss experimentally relevant parameters for ultracold ${}^{161}$ Dy.Interacting two-component Fermi gases are at the heart of our understanding of macroscopic quantum phenomena such as superconductivity. The changing nature of the interaction is expected to head to novel quantum phases. Here we study the ground state of a two-component fermionic gas in a harmonic potential with dipolar and contact interactions. Using a variational Wigner function we present the phase diagram of the system with equal but opposite values of the magnetic moment. We identify the second-order phase transition from paramagnetic to ferronematic phases. Moreover, we show the impact of the experimentally relevant magnetic field on the stability and magnetization of the system. We also investigate a two-component Fermi gas with large but almost equal values of the magnetic moment to study how the interplay between contact and dipolar interactions affects the stability properties of the mixture. To be specific we discuss experimentally relevant parameters for ultracold ${}^{161}$Dy.

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May 19, 20102 citations

{}^{161}

Dy.

We show that an antiferrosmectic-

C

phase has lower energy at high densities than the nonmagnetized Fermi gas and ferronematic phases in an ultracold gas of fermionic atoms, or molecules, with large magnetic dipole moments. This phase, which is analogous to meson condensation in dense nuclear matter, is a one-dimensional periodic structure in which the fermions localize in layers with their pseudospin direction aligned parallel to the layers and staggered layer by layer.

J

. The leading thermodynamic instabilities lie in the channels of ferromagnetism hybridized with the ferronematic order with

J={1}^{+}

and the spin-current mode with $J={1}^{\ensuremath{-}}$, where

+

and $\ensuremath{-}$ represent even and odd parities, respectively. An exotic propagating collective mode is identified as spin-orbit coupled Fermi surface oscillations in which spin distribution on the Fermi surface exhibits a topologically nontrivial hedgehog configuration.