Abstract-Terahertz charge dynamics unveil fundamental transport anisotropy in charge-ordered Pr 0.5 Eu 0.5 NiO 3 nickelate thin films

Sarmistha Das, G. L. Prajapati, Anagha P, and D. S. Rana

https://journals.aps.org/prb/accepted/ad074O16Ea9E1c1763c31290edb7c0df04b9f8b35

Electrons, condensed in a collective mode and behaving as free charge carriers, are two important facets induced by complex intertwining of charge, spin, orbital and lattice degrees of freedom. Existence of these two electronic ground states in the same structural/chemical phase is as much desired as much is elusive in complex oxides. Using some unique attributes of terahertz (THz) spectroscopy, we show existence of two fundamentally different electronic phenomena in Pr0.5Eu0.5NiO3, member of contemporary rare-earth nickelates, in the same orthorhombic phase but along two different orthogonal in-plane axes [001] and [1-10] of thin films. While a collective response of charge manifests via charge-density-wave (CDW) excitation along [001] direction, an entirely different Drude-Smith type free carrier response manifests along the other in-plane orthogonal axis. This anisotropy, on one hand, unveils the strained engineered crystallographic preferences of the underlying charge-ordering phenomenon, on the other hand, the different conduction channels open up the possibilities of application of nickelates such as in THz transmission modulators.