93Nb NMR study of the charge density wave
state in NbSe2
K Ghoshray, B Pahari, A Ghoshray, V V Eremenko,
V A Sirenko, and B H Suits
Abstract
93Nb NMR studies were carried out for a single
crystal of NbSe2 at 73.328 MHz in the temperature
range 9-300K to investigate the normal and charge density wave
(CDW) states. Detailed analysis of the NMR line shape of the
central transition using a classical incommensurate model
reveals the change in the conduction electron spin dynamics
from above TCDW. An increase of the Knight shift
below TCDW reflects modification to the uniform
part of the conduction electron density of states. As suggested
theoretically, the Knight shift distribution is found to be
directly proportional to the square of the amplitude of the
CDW. The results further indicate an incommensurate CDW
state in 2H-NbSe2. Analysis of the NMR spectra
using the McMillan incommensurate model suggests a large
value of the discommensuration parameter (gamma) which is
almost temperature independent, in constrast to the much
small value previously reported in the case of 2H-TaSe2.
Journal
of Physics: Condensed Matter 21, 155701 (2009).
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