$^{77}$Se and $^{63}$Cu NMR studies of the electronic correlations in Cu$_x$TiSe$_2$ ($x=0.05, 0.07$)

TL;DR

This study uses $^{77}$Se and $^{63}$Cu NMR to explore electronic correlations in Cu$_x$TiSe$_2$, revealing doping-dependent changes in relaxation rates and the importance of specific electronic bands at the Fermi level.

Contribution

It provides new insights into the electronic correlations and band contributions in Cu$_x$TiSe$_2$ through detailed NMR measurements and analysis.

Findings

Relaxation rates follow a linear temperature dependence at high fields.

Doping increases the slope of $^{77}$Se relaxation rate versus temperature.

Electronic correlations are significant, involving Se 4p and Ti 3d bands.

Abstract

We report $^{77}$Se and $^{63}$Cu nuclear magnetic resonance (NMR) investigation on the charge-density-wave (CDW) superconductor Cu$_x$TiSe$_2$ ($x=0.05$ and 0.07). At high magnetic fields where superconductivity is suppressed, the temperature dependence of $^{77}$Se and $^{63}$Cu spin-lattice relaxation rates 1/T_{1}$ follow a linear relation. The slope of $^{77}1/T_{1}$ vs \emph{T} increases with the Cu doping. This can be described by a modified Korringa relation which suggests the significance of electronic correlations and the Se 4\emph{p}- and Ti 3\emph{d}-band contribution to the density of states at the Fermi level in the studied compounds.