Systematic study of doping effect on the electronic structure of Cu$_{x}$NbSe$_{2}$

NbSe$_{2}$ is the one of the most studied transition metal dichalcogenide(TMD) materials. It has two phases : superconducting and charge density wave(CDW) phases. The superconductivity in NbSe$_{2}$ is known to be a conventional BCS superconductor. On the other hand, CDW mechanism in NbSe$_{2}$ cannot be explained by the conventional Fermi surface nesting scenario. To find out the exact mechanism of the CDW in NbSe$_{2}$, we try to change the electronic structure of NbSe$_{2}$ by Cu doping. In this presentation, we report the electronic structure studies of the Cu$_{x}$NbSe$_{2}$(x=0, 0.02, 0.04, 0.06, 0.08) measured by angle resolved photoemission spectroscopy (ARPES). We indeed observe doping effects on the electronic structure. The main effect is a Fermi surface topology change, which in turn modifies the nesting condition for CDW phase. To see the nesting condition more clearly, we performed auto-correlation analysis of the data. In addition, we studied the doping and temperature effects on the band renormalization and kink energy.