Interfacial Properties of Organic Semiconductor鈥揑norganic Magnetic Oxide Hybrid Spintronic Systems Fabricated Using Pulsed Laser Deposition

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• 作者：Sayani Majumdar ; Katarzyna Grochowska ; Miroslaw Sawczak ; Gerard 艢liwi艅ski ; Hannu Huhtinen ; Johnny Dahl ; Marjukka Tuominen ; Pekka Laukkanen ; Himadri S. Majumdar
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：October 14, 2015
• 年：2015
• 卷：7
• 期：40
• 页码：22228-22237
• 全文大小：561K
• ISSN：1944-8252

文摘

We report fabrication of a hybrid organic semiconductor鈥搃norganic complex oxide interface of rubrene and La_0.67Sr_0.33MnO₃ (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鈥搕in 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 A_g and B_g 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鈥揕SMO 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 AlO_x 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.