Conditions at the Electrochemical Interface and Their Relation to Electrodeposition of High Moment Soft CoFe Alloys

Abstract

Recent trends in magnetic recording and Micro-Electro-Mechanical System (MEMS) technologies favor electrodeposited Soft High Magnetic Moment (SHMM) alloys as the material of choice for fabrication of future magnetic devices [[1]-,[2],[3]]. The current efforts focus on synthesis of ultimately soft magnetic alloys with the maximum possible magnetic moment (2.4 T CoFe alloys), good corrosion resistance, high resistivity and low stress levels [3]. This seemingly difficult challenge is coupled with ever-continuing drive to miniaturize magnetic devices, bringing the electrodeposition to the level of nano-science [[4]-,[5][6]]. In this talk we will review our current understanding of the role of interfacial pH for obtaining good properties of magnetic alloys and nanostructures. The analytical model for Fe(OH)3 incorporation into deposit is presented with its relevance for control of CoFe alloy magnetic moment and coercivity. The analytical model is compared to experimental results illustrating incorporation of Fe-oxide species in CoFe alloys it is effect on magnetic moment and magnetic softness. Our attention is focused on presenting phenomenological relation between process parameters such as bulk pH, diffusion layer thickness, current efficiency etc.., and resulting oxygen content in CoFe alloys and their magnetic properties. The effective strategies for interfacial pH control, Fe3+ ion control and process design for manufacturing of CoFe nanostructures and thin films will be reviewed and their practical relevance for implementation in the real industrial conditions are discussed. The authors acknowledge the support from NSF Chemistry division under the contract # 0955922.[*] SRBrankovic@uh.edu[†] The Electrochemical Society active member REFERENCES:[1]) E. I. Cooper, C. Bonhote, J. Heidmann, Y. Hsu, P. Kern, J. W. Lam, M. Ramasubramanian, N. Robertson, L. T. Romankiw and H. Xu, IBM J. Res. & Dev., 49, 103 (2005). [2]) W. Ehrfeld, Electrochim. Acta, 48, 2857 (2003). [3]) S.R. Brankovic, N. Vasiljevic, N. Dimitrov, Chapter 27- Applications to Magnetic Recording and Microelectronic Technologies, Modern Electroplating V , editors: M. Paunovic and M. Schlesinger, John Willey and Sons, Inc (2010), p 573, [4]) X. M. Yang, H. Gentile, A. Eckert and S. R. Brankovic, J. Vac. Sci & Tech. B, 22, 3339 (2004). [5]) X. M. Yang, A. Eckert, K. Mountfield, H. Gentile, C. Seiler, S. R. Brankovic and E. Johns, J. Vac. Sci & Tech. B, 21, 3017 (2003). [6]) S. R. Brankovic , XM. Yang, T. J. Klemmer, and M. Seigler, IEEE Transactions on Magnetics, 42, 132 (2006).