Study of spin-valve operation in Permalloy-SiO2-Silicon nanostructures

• Published in: Journal of superconductivity 2003-02, Vol.16 (1), p.187-190
• Main Authors: HACIA, S, LAST, T, FISCHER, S. F, KUNZE, U
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity phenomena in semiconductors and insulators; Electronic transport in condensed matter; Exact sciences and technology; Galvanomagnetic and other magnetotransport effects; Physics; Spin polarized transport; Spin polarized transport in semiconductors
• ISSN: 0896-1107; 1572-9605
• DOI: 10.1023/A:1023242330715

Magnetotransport studies are performed on nanoscale Permalloy(Py)-(Mg)-SiO2-degenerate Si(100) tunneling devices in spin-valve geometry with and without Mg interlayer. Highly remanent, single domain Py electrodes (15-100-*mm length, 100-1000-nm width) are realized by electron-beam lithography, electron-beam evaporation, and subsequent lift-off. Different widths ensure subsequent switching of the Py nanoelectrodes in increasing magnetic fields. A suppression of spin-polarized current is expected for antiparallel magnetization configuration of source and drain contacts (i.e. positive magnetoresistance) if spin injection and detection have been successfully implemented. Magnetic hysteresis curves of Py nanowire arrays measured at temperatures from 5 K up to 300 K reveal increasing coercive fields (up to 40 mT) for decreased nanowire widths as required for device operation. Small positive magnetoresistance is observed for the spin-valve geometry with Mg interlayer at 4.2 K, contrary to the negative anisotropic magnetoresistance measured of single wires.