Pairing fluctuations and anisotropic pseudogap phenomenon in an ultracold superfluid Fermi gas with plural $p$-wave superfluid phases

Abstract

We investigate superfluid properties of a one-component Fermi gas with a uniaxially anisotropic $p$-wave pairing interaction, $U_x>U_y=U_z$ (where $U_i$ ($i=x,y,z)$ is a $p_i$-wave pairing interaction). This type of interaction is considered to be realized in a ${}^{40}$K Fermi gas. Including pairing fluctuations within a strong-coupling $T$-matrix theory, we determine the $p_x$-wave superfluid phase transition temperature $T_{\mathrm{c}}^{p_x}$, as well as the other phase transition temperature $T_{\mathrm{c}}^{p_x+i{p}_y}$ ($<T_{\mathrm{c}}^{p_x}$), below which the superfluid order parameter has the $p_x+i{p}_y$-wave symmetry. In the normal state near $T_{\mathrm{c}}^{p_x}$, $p_x$-wave pairing fluctuations are shown to induce an anisotropic pseudogap phenomenon, where a dip structure in the angle-resolved density of states around $\omega =0$ is the most remarkable in the $p_x$ direction. In the $p_x$-wave superfluid phase ($T_{\mathrm{c}}^{p_x+i{p}_y}<T\le T_{\mathrm{c}}^{p_x}$), while the pseudogap in the $p_x$ direction continuously changes to the superfluid gap, the pseudogap in the perpendicular direction to the $p_x$ axis is found to continue developing, because of enhanced $p_y$-wave and $p_z$-wave pairing fluctuations around the node of the $p_x$-wave superfluid order parameter. Since pairing fluctuations are always suppressed in the isotropic $s$-wave superfluid state, this phenomenon is peculiar to an unconventional Fermi superfluid with a nodal superfluid order parameter. Since the $p$-wave Fermi superfluid is the most promising non $s$-wave pairing state in an ultracold Fermi gas, our results would contribute to understanding how the anisotropic pairing fluctuations, as well as the existence of plural superfluid phases, affect many-body properties of this unconventional Fermi superfluid.

27 pages, 11 figures

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• Strongly-resonant p-wave superfluids
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• Trapped p-wave superfluids: a local density approach

Cited by in corpus (10)

• Non-Hermitian topological Fermi superfluid near the $p$-wave unitary limit
• Strong-Coupling and Finite Temperature Effects on $p$-wave Contacts
• Quantum fluctuations of a resonantly interacting $p$-wave Fermi superfluid in two dimensions
• Resonantly interacting $p$-wave Fermi superfluid in two dimensions: Tan's contact and breathing mode
• Strong-coupling Properties of a $p$-wave Interacting Fermi Gas on the Viewpoint of Specific Heat at Constant Volume
• Non-Hermitian $p$-wave superfluid and effects of the inelastic three-body loss in a one-dimensional spin-polarized Fermi gas
• Triplet pair amplitude in a trapped $s$-wave superfluid Fermi gas with broken spin rotation symmetry. II. Three dimensional continuum case
• Specific Heat and Effects of Uniaxial Anisotropy of a $p$-wave Pairing Interaction in a Strongly Interacting Ultracold Fermi Gas
• Shear Viscosity in the Strong Interaction Regime of a p-wave Superfluid Fermi Gas
• Appropriate conditions to realize a $p$-wave superfluid state starting from a spin-orbit coupled $s$-wave superfluid Fermi gas