Gapped optical excitations from gapless phases: imperfect nesting in unconventional density waves

TL;DR

This paper investigates how imperfect nesting affects the optical properties of quasi-one-dimensional unconventional density waves, revealing that deviations can induce optical gaps and spectral weight transfer, making their response resemble conventional density waves.

Contribution

It demonstrates that imperfect nesting can open optical gaps and alter spectral weight distribution in unconventional density waves, aligning their optical response with conventional density waves.

Findings

Optical gap opens with increased imperfect nesting.

Spectral weight shifts to higher frequencies.

Optical response becomes similar to conventional density waves.

Abstract

We consider the effect of imperfect nesting in quasi-one-dimensional unconventional density waves in the case, when the imperfect nesting and the gap depends on the same wavevector component. The phase diagram is very similar to that in a conventional density wave. The density of states is highly asymmetric with respect to the Fermi energy. The optical conductivity at T=0 remains unchanged for small deviations from perfect nesting. For higher imperfect nesting parameter, an optical gap opens, and considerable amount of spectral weight is transferred to higher frequencies. This makes the optical response of our system very similar to that of a conventional density wave. Qualitatively similar results are expected in d-density waves.