Investigating the Insulator to Metal transition in Hole Doped NdNiO₃ using Time-Domain THz Spectroscopy

NdNiO₃, a rare earth nickelate with a perovskite structure, displays an insulator-to-metal transition (IMT) and an antiferromagnetic transition around 160 K. However, if one hole dopes the system with calcium to form Nd_1-xCa_xNiO₃, the IMT is suppressed. We investigate the nature of this transition using time-domain terahertz (THz) spectroscopy (TDTS). Furthermore, we use time-resolved optical pump THz probe spectroscopy to map the dynamical change in the optical conductivity of these systems as a function of doping and temperature. We will discuss these results in the context of the competing structural and magnetic order in rare earth nickelates.