Wide band XRD study of 2H-NbSe2 in a CDW-regime

Albeit rather simple structure and ample experimental study of charge density wave (CDW) superconductor 2H-NbSe2 its behaviour in a CDW regime (TCDW = 32.5 K, TSN = 7.2 K) remains unclear. The relevance of the known mechanisms of CDW formation to this hexagonal modification of the niobium diselenide is not straightforward. Occurrence of the lock-in transition in this compound is still debated despite numerous structural investigations by means of diverse diffraction techniques. Here, we present Debye patterns measured in a detail at temperatures 8-35 K with different sources of X-ray irradiation and energy resolution of about 1eV. New features observed in the temperature range 15-30 K are discussed in terms of fluctuation-mediated phase transition.