Zero sound in a two-dimensional dipolar Fermi gas

We study zero sound in a weakly interacting two-dimensional (2D) gas of single-component fermionic dipoles (polar molecules or atoms with a large magnetic moment) tilted with respect to the plane of their translational motion. It is shown that the propagation of zero sound is provided by both mean-field and many-body (beyond mean field) effects, and the anisotropy of the sound velocity is the same as the one of the Fermi velocity. The damping of zero sound modes can be much slower than that of quasiparticle excitations of the same energy. One thus has wide possibilities for the observation of zero sound modes in experiments with 2D fermionic dipoles, although the zero sound peak in the structure function is very close to the particle-hole continuum.

Figure 1

2D gas of dipoles tilted by an angle ${\theta }_0$ in the $x,z$ plane.

Figure 2

Dynamical structure factor [in units of $m/{\left(2\pi {\hslash }^2\right)}^2$] as a function of $\omega /k{v}_F$ for $s_0=1.05$.