We investigate the specific heat
CV at constant volume and effects of uniaxial anisotropy of a
p-wave attractive interaction in the normal state of an ultracold Fermi gas. Within the framework of the strong-coupling theory developed by Nozières and Schmitt-Rink, we evaluate this thermodynamic quantity as a function of temperature, in the whole interaction regime. While the uniaxial anisotropy is not crucial for
CV in the weak-coupling regime,
CV is found to be sensitive to the uniaxial anisotropy in the strong-coupling regime. This originates from the population imbalance among
pi-wave molecules (
i=x,y,z), indicating that the specific heat is a useful observable to see which kinds of
p-wave molecules dominantly exist in the strong-coupling regime when the
p-wave interaction has uniaxial anisotropy. Using this strong point, we classify the strong-coupling regime into some characteristic regions. Since a
p-wave pairing interaction with uniaxial anisotropy has been discovered in a
40K Fermi gas, our results would be useful in considering strong-coupling properties of a
p-wave interacting Fermi gas, when the interaction is uniaxially anisotropic.
We investigate the superfluid properties of a one-component Fermi gas with a uniaxially anisotropic
p-wave pairing interaction,
Ux>Uy=Uz [where
Ui(i=x,y,z) is a
pi-wave pairing interaction]. This type of interaction is considered to be realized in a
40K Fermi gas. Including pairing fluctuations within a strong-coupling
T-matrix theory, we determine the
px-wave superfluid phase transition temperature
Tcpx, as well as the other phase transition temperature
Tcpx+ipy(<Tcpx), below which the superfluid order parameter has the
px+ipy-wave symmetry. In the normal state near
Tcpx,px-wave pairing fluctuations are shown to induce an anisotropic pseudogap phenomenon, where a dip structure in the angle-resolved density of states around $\ensuremath{\omega}=0$ is the most remarkable in the
px direction. In the
px-wave superfluid phase $({T}_{\mathrm{c}}^{{p}_{x}+i{p}_{y}}<T\ensuremath{\le}{T}_{\mathrm{c}}^{{p}_{x}})$, while the pseudogap in the
px direction continuously changes to the superfluid gap, the pseudogap in the perpendicular direction to the
px axis is found to continue developing because of enhanced
py-wave and
pz-wave pairing fluctuations around the node of the
px-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.
We theoretically investigate the specific heat at constant volume C V in the BCS(Bardeen-Cooper-Schrieffer)-BEC(Bose-Einstein-condensation)-crossover regime of an ultracold Fermi gas, below the superfluid phase transition temperature T c . Within the strong-coupling framework developed by Nozières and Schmitt-Rink, we show that the temperature dependence of C V drastically changes as one passes through the crossover region, and is sensitive to strong fluctuations in the Cooper channel near the unitarity limit. We also compare our results to a recent experiment on a 6 Li unitary Fermi gas. Since fluctuation effects are a crucial key in the BCS-BEC-crossover phenomenon, our results would be helpful in considering how the fermionic BCS superfluid changes into BEC with increasing the interaction strength, from the viewpoint of specific heat.