62 research outputs found
Collective excitations and screening in two-dimensional tilted nodal-line semimetals
Topological nodal-line semimetals are characterized by symmetry-protected
one-dimensional band-touching lines or loops, which give rise to their peculiar
Fermi surfaces at low energies. Furthermore, if time-reversal or inversion
symmetry breaking tilts the bands, anisotropic Fermi surfaces hosting electron
and hole carriers simultaneously can also appear. We analytically investigate
the linear density-density response function of a two-dimensional tilted
nodal-line semimetal in the intrinsic and doped regimes. Despite the
anisotropic electronic bands, the polarizability remains isotropic in our model
system. We find that the plasmon dispersion in the long wavelength limit
exhibits a standard behavior that is proportional to the square root of the
wave vector, characteristic of two-dimensional electron liquids. Tilting tends
to enhance the plasmon frequency, and the Drude weight does not depend on the
carrier density at low doping levels. In these regimes, unlike the intrinsic
and highly-doped ones, the static polarizability has two distinct singularities
at finite wave vectors. This results in beat patterns in the Friedel
oscillations.Comment: 8 pages, 7 figures, submitte
- …