Universal renormalization group flow toward perfect Fermi-surface nesting driven by enhanced electron-electron correlations in monolayer vanadium diselenide

TL;DR

This study demonstrates that in monolayer VSe₂, imperfect Fermi surface nesting universally evolves into perfect nesting due to electron-electron correlations, leading to enhanced charge density wave transition temperatures.

Contribution

It provides a renormalization group analysis showing the universal flow from imperfect to perfect Fermi surface nesting in two dimensions, explaining the high CDW transition temperature.

Findings

Fermi velocity along the orthogonal direction vanishes at perfect nesting.

Imperfect nesting flows into perfect nesting in two dimensions.

CDW transition temperature exceeds 300 K in monolayer VSe₂.

Abstract

In the present study we examine nature of a charge ordering transition in monolayer vanadium diselenide ($VSe_{2}$), which would be distinguished from that of $VSe_{2}$ bulk samples, driven by more enhanced electron-electron correlations. Recently, angle resolved photoemission spectroscopy measurements uncovered that the Fermi surface nesting becomes perfect, where the dynamics of hot electrons is dispersionless along the orthogonal direction of the nesting wave-vector. In addition, scanning tunneling microscopy measurements confirmed that the resulting CDW state shows essentially the same modulation pattern as the three dimensional system of $VSe_{2}$. Here, we perform the renormalization group analysis based on an effective field theory in terms of critical CDW fluctuations and hot electrons of imperfect Fermi-surface nesting. As a result, we reveal that the imperfect nesting universally flows into perfect nesting in two dimensions, where the Fermi velocity along the orthogonal direction of the nesting vector vanishes generically. We argue that this electronic reconstruction is responsible for the observation that the CDW transition temperature is much more enhanced to be around $T_{c} > 300$ $K$ than that of the bulk sample.