Enhanced Optical Response in Au Nanopillar/La0.67Sr0.33MnO3 Film Composites: Implications for Magnetooptical Devices

Metal oxide vertically aligned nanocomposite thin films have been of considerable interest for hot-carrier-based light harvesting and active plasmonic applications. Herein, we present femtosecond pump-probe spectroscopy studies on a nano composite thin film with plasmonic Au nanopillars vertically aligned in a ferromagnetic La0.67Sr0.33MnO3 (LSMO) matrix. Our measurements reveal that the carrier decay of Au/LSMO films qualitatively follows that of pure LSMO with a two-component relaxation. In the presence of Au nanopillars, the charge generation within the LSMO film is enhanced by a factor of similar to 40, and the spin-lattice relaxation time associated with demagnetization is substantially decreased from 259.6 to 7.7 ps. The enhanced nonequilibrium dynamics and energy transfer between the lattice and spin system in the Au/LSMO films can be well modeled using an extended three-temperature model. These Au/LSMO thin films can be potentially useful in ultrafast photoelectric and magnetooptical applications.

Automated summary

Metal oxide vertically aligned nanocomposite thin films with plasmonic Au nanopillars in a ferromagnetic La0.67Sr0.33MnO3 (LSMO) matrix were studied using femtosecond pump-probe spectroscopy. The presence of Au nanopillars enhanced the charge generation and decreased the spin-lattice relaxation time in LSMO, as compared to pure LSMO. The nonequilibrium dynamics and energy transfer in the Au/LSMO films were well modeled using an extended three-temperature model. These thin films have potential applications in ultrafast photoelectric and magnetooptical devices.