Resistivity of nanostructured Fe–Cr films C. Heck a, * , A. Chayahara a , Y. Horino a , R. Funahashi b , R.M.N. Miranda c,d , M.N. Baibich d a Laboratory of Purified Materials, National Institute of Advanced Industrial Science and Technology, AIST Kansai, Ikeda, Osaka 563-8577, Japan b Special Division for Green Life Technology, National Institute of Advanced Industrial Science and Technology, AIST Kansai, Ikeda, Osaka, Japan c Centro Universit  ario FEEVALE, Novo Hamburgo, RS, Brazil d Instituto de F  ısica, UFRGS, Porto Alegre, RS, Brazil Abstract ThepresentworkreportsonthestructuralandtransportpropertiesofnanostructuredFeinthinCrfilms,produced byimplantationofFe þ ions.Theimplantationprocessintroducesdefectsinthesefilmsforcingaccommodationtotake place during and after the process that induce the segregation of immiscible species. This gives rise to the nanostruc- tured Fe granules in much faster time scales than when conventional processes are used. A comparison is made with systems produced by depositing Fe between Cr layers by means of the arc-vacuum deposition method at equivalent concentrations. Resistivity versus temperature curve shows a clear minimum at fairly high temperatures for the implanted samples only. This effect is probably due to electronic interactions with the Fe nanostructures formed by segregation and to coupling with defects. Ó 2003 Elsevier Science B.V. All rights reserved. PACS: 73.63.Bd; 81.07.Bc Keywords: Ion implantation; Nanostructures; Fe; Cr 1. Introduction The behaviour of FeCr alloys in the non-equi- librium region, where spinodal decomposition is observed, has been the subject of many papers dealing with its physical properties over the years. Recently some of us pointed out that spinodal decomposition might be at the origin of the giant magnetoresistance (GMR) observed in other non- equilibriumsystems(asinCuCo).ThefactthatFe and Cr were the components of the original sam- ples where GMR was discovered [1] only adds to the interest these materials arise. In our particular case,wesetouttostudytheevolutionofCrfilms bombarded with Fe ions at energies that would correspond to the formation of a rather heavy Fe layer within the Cr film. By annealing the bom- barded samples, the evolution of the iron concen- trateswouldthenbestudied.Ascanbeseeninthe * Corresponding author. Tel.: +81-727-51-9531; fax: +81- 727-51-9631. E-mail address: heck.claire@aist.go.jp (C. Heck). 0168-583X/03/$ - see front matter Ó 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0168-583X(03)00776-6 Nuclear Instruments and Methods in Physics Research B 206 (2003) 601–605 www.elsevier.com/locate/nimb