4th INTERNATIONAL WORKSHOP ON ELECTRODEPOSITED NANOSTRUCTURES 16-18 March 2006, Dresden, Germany	ABSTRACTS

SYNTHESIS AND MAGNETOTRANSPORT PROPERTIES OF FERROMAGNETIC MULTILAYER NANOWIRES Jie Gong1,2 and Giovanni Zangari2,3 1) Materials Science Program and 2) MINT Center, University of Alabama, Tuscaloosa AL 35487 3) Dept of Materials Science and Engineering and CESE, University of Virginia, Charlottesville VA 22904 USA Low-dimensional nanomaterials have recently received considerable attention due to their unique properties as well as their potentially wide applications in magnetic, electronic, and optoelectronic structures and devices. In particular, the template-synthesis method based on electrodeposition into ordered anodic aluminum oxide has attracted great interest for the fabrication of nanowire arrays. Templated electrodeposition processes have been reported to produce magnetic nanowires exhibiting current perpendicular to plane giant magnetoresistance (CPP-GMR), and current-induced magnetization switching. We used anodization and post-processing of both free-standing and silicon-supported aluminium films to synthesize Al oxide templates with closely controlled pore diameter, lengths and opening of the barrier layer. The latter in free-standing Al oxide films can be reproducibly controlled down to 5 nm by using ion beam etching. The electrodeposition process of FeCoNi/Cu multilayers in Al oxide templates was first addressed by performing a comprehensive study of the electrodeposition of multilayer films on n-type Si. The influence of Cu deposition potential and Fe2+ concentration on microstructural, magnetic and magnetotransport properties was assessed. In particular, the dissolution of the ferromagnetic FM layer during the potential transitions was minimized in order to control interface sharpness. By systematically varying sublayer thickness and FM layer composition, an unprecedented GMR sensitivity of 0.11%/Oe at 5-15 Oe was obtained. Based on these results the process of electrodepositing multilayer nanowires was optimized by minimizing FM layer dissolution. Electrical contact to single multilayer wires was attempted using an electrochemical technique to stop the growth process when contact first occurred. In this way, we succeeded in addressing a small number of nanowires and measured a CPP-GMR of 17%. Template electrodeposition was demonstrated to provide a promising route towards the repeatable fabrication of prototype material systems for spin dependent transport studies.

 
 
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