Charge order inNbSe2

Abstract

We develop in detail a model of the charge order in NbSe2 deriving from a strong electron-phonon coupling dependent on the ingoing and outgoing electron momenta as well as the electronic orbitals scattered between. Including both dependencies allows us to reproduce the full range of available experimental observations on this material. The stability of both experimentally-observed chargeordered geometries (1Q and 3Q) is studied within this model as a function of temperature and uniaxial strain. It is found that a small amount of bulk strain suffices to stabilize the unidirectional order, and that in both ordering geometries, lattice fluctuations arising from the strong electronphonon coupling act to suppress the onset temperature of charge order, giving a pseudogap regime characterized by local order and strong phase fluctuations.

Competing Coulomb and electron–phonon interactions in NbS2

“…70 meV. This is comparable to the g max = 0.13 eV found by Flicker and van Wezel [35] for bulk NbSe 2 .…”

“…Here, the V-based compounds show tendencies towards magnetic [19,20] as well as charge order [21][22][23] in their monolayer and bulk phases, respectively, which might partially coexist in the few-layer limit [20,24]. In contrast, the sub-class of Ta-based compounds [1,[25][26][27][28][29][30] as well as NbSe 2 [2,3,[31][32][33][34][35][36][37][38] show a competition between charge-density waves, superconducting as well as Mott insulating states. NbS 2 appears to be a border case.…”

General theoretical description of angle-resolved photoemission spectroscopy of van der Waals structures

“…We would like to point out that the present formalism can also be applied to model ARPES in other system subject to competing periodicities, such as systems displaying CDWs [52] or 2D materials weakly coupled to a substrate.…”

Spectroscopic signature of moment-dependent electron–phonon coupling in 2H-TaS2

“…A prototypical example of a many-body interaction is the electronphonon (el-ph) interaction, whose significance can't be overemphasized in TMDs, particularly in 2H polytypes of TMDS such as 2H-TaSe 2 , 2H-NbSe 2 and 2H-TaS 2 (hereinafter collectively referred to as 2H TMDs). The reason is that the el-ph coupling is central to both superconductivity 11 and CDW [12][13][14] , which either coexist or compete in these materials.…”