Magnetic disparities at the interfaces of Co–pentacene–Co hybrid structures

• Published in: Synthetic metals Vol. 161; no. 7; pp. 581 - 585
• Main Authors: Wei, D.H., Chan, Yuet-Loy, Hung, Ya-Jyuan, Wang, Chia-Hao, Lin, Ying-Chang, Lai, Yu-Ling, Chang, Hsu-Ting, Lee, Chih-Hao, Hsu, Y.J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2011; Elsevier
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Interface; Magnetic domain; Magnetoelectric, magnetostrictive, magnetoacoustic, magnetooptic and magnetothermal devices. Spintronics; Organic spin-valve; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; X-ray magnetic circular dichroism; X-ray magnetic circular dichroism; Organic spin-valve; Interface; Magnetic domain; Ultrathin films; Pentacene; Spin valve; Ferromagnetic materials; Electron microscopy; Cobalt; Photoemission; Dichroism; Organic semiconductors; Bilayers; Organic electronics; X-ray photoelectron spectra
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2011.01.009

We investigated two series of ultrathin ferromagnet-organic semiconductor (FM-OSC) hybrid structures fabricated with reversed layer orders in ultra-high vacuum conditions to emulate the interfaces of FM/OSC/FM organic spin-valves. Using X-ray photoemission electron microscopy (PEEM), the magnetic responses of the cobalt (Co) layer in contact with the pentacene (Pc) film were investigated on a microscopic scale. According to the PEEM images acquired on Pc (1.8 nm)/Co bilayers, the Co top layer was found to turn on its ferromagnetic order after its thickness reaches 2.2 nm. Also, upon the onset of magnetic contrast, the element-specific images revealed that the Pc/Co bilayers exhibit a complex domain pattern whose average dimension is at least two orders of magnitude smaller than that of the pattern found in Co (2.4 nm)/Pc bilayers. Further X-ray photoelectron spectroscopy investigations suggest that the magnetic disparities observed between Co/Pc and Pc/Co bilayers are correlated with the different chemistries occurred at their interfaces.