Terahertz conductivity across the insulator-metal transition of epitaxial Praseodymium Nickel Oxide thin films

Here we report the low energy (0.8–7 meV) charge dynamics probed by Terahertz time domain transmission spectroscopy on 40 nm thick PrNiO
3
(PNO) thin films deposited on the (LaAlO
3
)
0.3
(Sr
2
TaAlO
6
)
0.7
(LSAT) (110) substrate grown by pulsed laser deposition method. We have experimentally investigated both complex dielectric constant and optical conductivity spectra with respect to temperature ranging from 5 K to 300 K. Terahertz optical conductivity for PNO thin films shows two I-M transitions at 130 K (similar to that of the bulk PNO) and a re-entrant I-M transition around 25 K. The behavior of reentrant I-M transition at 25 K may be due to the presence of Pr
2
NiO
4
minor impurity phase.