journal of materials processing technology 208 ( 2 0 0 8 ) 409–414 journal homepage: www.elsevier.com/locate/jmatprotec Evidence of giant magnetoresistance effect in heterogeneous nanogranular films produced by ultrashort pulsed laser deposition V. Iannotti a,* , S. Amoruso b , G. Ausanio a , A.C. Barone a , C. Campana c , C. Hison a , L. Lanotte a a CNR-INFM Coherentia, Dip.to di Scienze Fisiche, Universit` a degli Studi di Napoli “Federico II”, P.le V. Tecchio 80, I-80125 Napoli, Italy b CNR-INFM Coherentia, Dip.to di Scienze Fisiche, Universit` a degli Studi di Napoli “Federico II”, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli, Italy c CNR-INFM Coherentia, Dip.to di Ingegneria dei Materiali e della Produzione, Universit` a degli Studi di Napoli “Federico II”, P.le V. Tecchio 80, I-80125 Napoli, Italy article info Article history: Received 28 July 2007 Received in revised form 12 November 2007 Accepted 5 January 2008 Keywords: Ultrashort pulsed laser deposition Nanogranular magnetic films Magnetoresistance GMR effect abstract Giant magnetoresistance effect is found in films of magnetic nanoparticles uniformly mixed with non-magnetic metallic nanoparticles produced by ultrashort pulsed laser deposition (uPLD). The uPLD, which uses femtosecond laser pulses, has been recently reported as a pow- erful technique for obtaining nanoparticles and nanogranular films. As-deposited Co–Cu and Fe–Ag films in a moderate volume fraction range of magnetic component (15–25%) present detectable values of this magnetoresistive effect, although the average size of the particles is higher than in typical nanogranular materials for magnetoresistive appli- cations. The determined longitudinal, transverse and perpendicular magnetoresistance behaviours, at the temperatures of 10 and 250 K, confirm the strong influence of the pro- duction technique on the complex microstructure of these films and consequently on their peculiar magneto-transport properties. In perspective, by optimizing the production param- eters, these nanogranular films appear very promising for potential application in magnetic recording and data storage technology. © 2008 Elsevier B.V. All rights reserved. 1. Introduction The 90 years have seen an increasing focus on the study of nanogranular metallic systems made by simultaneous depo- sition of mutually immiscible magnetic and non-magnetic elements. The pioneering works of Berkowitz et al. (1992) and Xiao et al. (1992) indicate that these binary systems show giant magnetoresistance (GMR) effect, which was initially discov- ered in antiferromagnetically coupled multilayers (Baibich et ∗ Corresponding author. Tel.: +39 081 7682612; fax: +39 081 2391821. E-mail address: iannotti@na.infn.it (V. Iannotti). al., 1988; Binasch et al., 1989). The prevailing GMR physical picture (Zhang and Levy, 1993; Wang and Xiao, 1995) is based on the existence of two independent currents made each one of spin-up and spin-down electrons, which are scattered by the magnetic components with different rates, depending mainly on the relative orientation between the electron spin and the magnetic moment vector of the scatterer. The appli- cation of sufficiently large magnetic fields gradually aligns these scatterers magnetic moments, increasing the macro- 0924-0136/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2008.01.005