Point-contact tunneling spectroscopy measurement of CuxTiSe2: Disorder-enhanced Coulomb effects

Abstract

We performed point-contact spectroscopy tunneling measurements on CuxTiSe2 bulk with x=0.02 and 0.06 at temperatures ranging from T=4−40 K and observe a suppression in the density of states around zero bias that we attribute to enhanced Coulomb interactions due to disorder. We find that the correlation gap associated with this suppression is related to the zero-temperature resistivity. We use our results to estimate the disorder-free transition temperature and find that the clean limit Tc0 is close to the experimentally observed Tc at optimal doping.