title: Interfacial Properties of Organic Semiconductor-Inorganic Magnetic Oxide Hybrid Spintronic Systems Fabricated Using Pulsed Laser Deposition.
abstract: We report fabrication of a hybrid organic semiconductor-inorganic complex oxide interface of rubrene and La0.67Sr0.33MnO3 (LSMO) for spintronic devices using pulsed laser deposition (PLD) and investigate the interface structure and chemical bonding-dependent magnetic properties. Our results demonstrate that with proper control of growth parameters, thin films of organic semiconductor rubrene can be deposited without any damage to the molecular structure. Rubrene, a widely used organic semiconductor with high charge-carrier mobility and spin diffusion length, when grown as thin films on amorphous and crystalline substrates such as SiO2-glass, indium-tin oxide (ITO), and LSMO by PLD at room temperature and a laser fluence of 0.19 J/cm2, reveals amorphous structure. The Raman spectra verify the signatures of both Ag and Bg Raman active modes of rubrene molecules. X-ray reflectivity measurements indicate a well-defined interface formation between surface-treated LSMO and rubrene, whereas X-ray photoelectron spectra indicate the signature of hybridization of the electronic states at this interface. Magnetic measurements show that the ferromagnetic property of the rubrene-LSMO interface improves by >230% compared to the pristine LSMO surface due to this proposed hybridization. Intentional disruption of the direct contact between LSMO and rubrene by insertion of a dielectric AlOx layer results in an observably decreased ferromagnetism. These experimental results demonstrate that by controlling the interface formation between organic semiconductor and half-metallic oxide thin films, it is possible to engineer the interface spin polarization properties. Results also confirm that by using PLD for consecutive growth of different layers, contamination-free interfaces can be obtained, and this finding is significant for the well-controlled and reproducible design of spin-polarized interfaces for future hybrid spintronics devices.
authors.affiliation: Department of Applied Physics, Aalto University School of Science , FI-00076 Aalto, Finland.
authors.forename: Sayani
authors.initials: S
authors.lastname: Majumdar
authors.affiliation: Photophysics Department, The Szewalski Institute, Polish Academy of Sciences , 80-231 Gdansk, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Grochowska
authors.affiliation: Photophysics Department, The Szewalski Institute, Polish Academy of Sciences , 80-231 Gdansk, Poland.
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Sawczak
authors.affiliation: Photophysics Department, The Szewalski Institute, Polish Academy of Sciences , 80-231 Gdansk, Poland.
authors.forename: Gerard
authors.initials: G
authors.lastname: Śliwiński
authors.affiliation: Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku , FI-20014 Turku, Finland.
authors.forename: Hannu
authors.initials: H
authors.lastname: Huhtinen
authors.affiliation: Materials Research Laboratory, Department of Physics and Astronomy, University of Turku , FI-20014 Turku, Finland.
authors.forename: Johnny
authors.initials: J
authors.lastname: Dahl
authors.affiliation: Materials Research Laboratory, Department of Physics and Astronomy, University of Turku , FI-20014 Turku, Finland.
authors.forename: Marjukka
authors.initials: M
authors.lastname: Tuominen
authors.affiliation: Materials Research Laboratory, Department of Physics and Astronomy, University of Turku , FI-20014 Turku, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Laukkanen
authors.affiliation: VTT Technical Research Center of Finland , FI-02150 Espoo, Finland.
authors.forename: Himadri S
authors.initials: HS
authors.lastname: Majumdar
keywords: hybrid interface; magnetic properties; organic semiconductor thin films; organic spintronics; pulsed laser deposition