Emergence of coherence in the charge-density wave state of 2H-NbSe2

• DOI: 10.1038/ncomms7313
• Publication Date: 2015-02-17T09:58:44Z
• Authors: U. Chatterjee; J. Zhao; M. Iavarone; R. Di Capua; J. P. Castellan; G. Karapetrov; C. D. Malliakas; M. G. Kanatzidis; H. Claus; J. P. C. Ruff; F. Weber; J. van Wezel; J. C. Campuzano; R. Osborn; M. Randeria; N. Trivedi; M. R. Norman; S. Rosenkranz
• Keywords: Charge Density Wave; Pseudogap

A charge-density wave (CDW) state has a broken symmetry described by complex order parameter with an amplitude and phase. The conventional view, based on clean, weak-coupling systems, is that finite long-range phase coherence set in simultaneously at the CDW transition temperature T$_{cdw}$. Here we investigate, using photoemission, X-ray scattering scanning tunneling microscopy, canonical compound 2H-NbSe$_2$ intercalated Mn Co, show view untenable. We find that, either high or large intercalation, becomes short-ranged well-defined impacts electronic dispersion, giving rise to energy gap. T$_{cdw}$ marks onset of global coherence, leading sharp excitations. Our observations emphasize importance fluctuations strongly coupled systems provide insights into significance incoherence `pseudogap' states.