Fluctuation effects at the onset of the 2kF density wave order with one pair of hot spots in two-dimensional metals

Abstract

We analyze quantum fluctuation effects at the onset of charge or spin density wave order in twodimensional metals with an incommensurate 2kF wave vector connecting a single pair of hot spots on the Fermi surface. We compute the momentum and frequency dependence of the fermion selfenergy near the hot spots to leading order in a fluctuation expansion (one loop). Non-Fermi liquid behavior with anomalous frequency scaling and a vanishing quasi particle weight is obtained. The momentum dependence yields a divergent renormalization of the Fermi velocity and a flattening of the Fermi surface near the hot spots. Going beyond the leading order calculation we find that the one-loop result is not self-consistent. We show that any momentum-independent self-energy with a non-Fermi liquid frequency exponent wipes out the peak of the polarization function at the 2kF wave vector, and thus destroys the mechanism favoring 2kF density waves over those with generic wave vectors. However, a 2kF density wave quantum critical point might survive in presence of a sufficiently flat renormalized Fermi surface.

2kF density wave instability of composite Fermi liquid

“…We should note that it is still under debate whether the 2k F density wave transition is continuous. While Altshuler et al [36] argues that a first-order transition occurs due to the strong 2k F fluctuation at low energies, a more recent article by Sykora et al [37] shows a second-order transition is also possible. It will also be an excellent task to investigate the critical phenomena in 2k F transitions of NFL, which we leave for future work.…”

“…In this paper, we propose one mechanism to reap yet another instability of CFL: the 2k F density wave instability, which is of equal importance to the previously discovered CFL instabilities and is likely to exhibit distinct physics from ordinary Fermi liquids [36][37][38]. Based on an exact diagonalization (ED) and renormalization group (RG) analysis, we propose one possible mechanism to trigger the density wave instability of CFL on half-filled LLs: tuning the interactions via the mixed LL form factors from an anisotropic CFL state.…”

${\bf 2k_F}$ Density Wave Instability of Composite Fermi Liquid

“…We should note that it is still under debate whether the 2k F density-wave transition is continuous. While Altshuler et al [30] argues a first-order transition due to the strong 2k F fluctuation at low energies, a more recent article by Sykora et al [31] shows a second-order transition is also possible. It will also be an excellent task to investigate the critical phenomena in 2k F transition of NFL, which we leave for future works.…”

“…In this letter, we would like to reap yet another natural instability of CFL: the 2k F density-wave instability, which is of equal importance to the previously discovered CFL instabilities and is likely to exhibit distinct physics from the ordinary Fermi liquids [30][31][32]. Based on the exact diagonalization (ED) and renormalization group (RG) analysis, we propose one possible mechanism to trigger the density-wave instability of CFL on half filled LLs: tuning the interactions via the mixed LL form factors from an anisotropic CFL state.…”

A potential all-electronic route to the charge-density-wave phase in monolayer vanadium diselenide

“…Many TMDs exhibit CDW phases with rather high critical temperatures, which are often further enhanced in the monolayer limit 5 . One well known route to CDW formation is via Fermi surface nesting: here sections of the Fermi surface lie parallel to each other, giving an enhanced particle-hole susceptibility at a non-zero wavevector Q [6][7][8][9][10] . This is an inherently electronic mechanism.…”