Low energy dynamics in charge ordered R0.5Sr0.5MnO3 (R = Nd and Pr) manganite thin films


Low energy dynamics in charge ordered R0.5Sr0.5MnO3 (R = Nd and Pr) manganite thin films

Rana, R.; Schmidt, J.; Grenzer, J.; Schneider, H.; Helm, M.; Pashkin, A.

Transition metal oxides represent an exotic class of correlated systems in which a complex interplay between the spin, charge, orbital and lattice degrees of freedom may result in colossal magnetoresistance, superconductivity; charge ordered (CO) phases, etc. The half-doped Pr0.5Sr0.5MnO3 manganite represents a unique stripe type CO-orbital order that induces transport and magnetic anisotropy whereas the CO in Nd0.5Sr0.5MnO3 is charge-exchange (CE)-type which is isotropic in nature.

We have systematically explored ~ 200nm epitaxial manganite thin films grown on (100), (110), and (111) oriented (LaAlO3)0.3(Sr2TaAlO6)0.7 substrates by pulsed laser deposition technique. Our Terahertz (THz) time-domain spectroscopic data reveal charge density wave (CDW) resonance centered around 5-6 meV for (110) oriented films and Drude-like conductivity for (100) and (111) oriented films. The CDW resonance in the optical conductivity spectra can be tuned from 4 meV to 6 meV for (110) oriented films and depends on the amount of ferromagnetic phase fraction in the CO matrix and corroborates well with the magnetization measurements. The nonlinear conductivity related to the sliding of the pinned CDW character makes the studied systems promising candidates for ultrafast coherent control of charge transport by resonant THz pumping.

Keywords: Manganites; charge order; terahertz

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Publ.-Id: 26817