Terahertz spectroscopic evidence of non-Fermi-liquid-like behavior in structurally modulated PrNiO3 thin films

Abstract

The intertwined and competing energy scales of various interactions in rare-earth nickelates $R\mathrm{Ni}{\mathrm{O}}_{3}$ ($R=\mathrm{La}$ to Lu) hold potential for a wide range of exotic ground states realized upon structural modulation. Using terahertz (THz) spectroscopy, the low-energy dynamics of a novel non-Fermi liquid (NFL) metallic phase induced in compressive $\mathrm{PrNi}{\mathrm{O}}_{3}$ thin film was studied by evaluating the quasiparticle scattering rate in the light of two distinct models over a wide temperature range. First, evaluating THz conductivity in the framework of extended Drude model, the frequency-dependent scattering rate is found to deviate from the Landau Fermi liquid (LFL) behavior, thus, suggesting NFL-like phase at THz frequencies. Second, fitting THz conductivity to the multiband Drude-Lorentz model reveals the band-dependent scattering rates and provides microscopic interpretation of the carriers contributing to the Drude modes. This is first evidence of NFL-like behavior in nickelates at THz frequencies consistent with dc conductivity, which also suggests that THz technology is indispensable in understanding emerging electronic phases and associated phenomena. We further demonstrate that the metal-insulator transition in nickelates has the potential to design efficient THz modulators.