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arXiv · 2303.08580

Collective modes in the charge-density wave state of K$_{0.3}$MoO$_3$: The role of long-range Coulomb interactions revisited

Max O. Hansen·Yash Palan·Viktor Hahn·Mark D. Thomson·Konstantin Warawa·Hartmut G. Roskos·Jure Demsar·Falko Pientka·Oleksandr Tsyplyatyev·Peter Kopietz
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Abstract

We re-examine the effect of long-range Coulomb interactions on the collective amplitude and phase modes in the incommensurate charge-density-wave ground state of quasi-one-dimensional conductors. Using an effective action approach we show that the longitudinal acoustic phonon protects the gapless linear dispersion of the lowest phase mode in the presence of long-range Coulomb interactions. Moreover, in Gaussian approximation, amplitude fluctuations are not affected by long-range Coulomb interactions. We also calculate the collective mode dispersions at finite temperatures and compare our results with the measured energies of amplitude and phase modes in K$_{0.3}$MoO$_3$. With the exception of the lowest phase mode, the temperature dependence of the measured mode energies can be quantitatively described within a multi-phonon Fr\"{o}hlich model for generic electron-phonon interactions neglecting long-range Coulomb interactions.

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Max O. Hansen, Yash Palan, Viktor Hahn, Mark D. Thomson, Konstantin Warawa, Hartmut G. Roskos, Jure Demsar, Falko Pientka, Oleksandr Tsyplyatyev, Peter Kopietz. 2023-03-15. Collective modes in the charge-density wave state of K$_{0.3}$MoO$_3$: The role of long-range Coulomb interactions revisited. https://doi.org/10.1103/physrevb.108.045148

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