Analysis of the magnetoresistance contributions in a nanocrystallized Cr-doped FINEMET alloy

The magnetoresistance (MR) was measured at 200, 250 and 300 K in magnetic fields up to B=12 T for a nanocrystallized Fe63.5Cr 10Nb3Cu1Si13.5B9 alloy. Both the longitudinal (LMR) and transverse (TMR) component of the magnetoresistance decreased from B=0 to about 0.1 T. This could be ascribed to a giant MR (GMR) effect due to spin-dependent scattering of conduction electrons along their path between two FeSi nanograins via the non-magnetic matrix. Such a scattering may occur if the nanograin moments are not or only weakly coupled in the absence of a strong exchange coupling (due to the high Cr content in the matrix) and/or only weak dipoledipole coupling is present (due to sufficiently large separations between the nanograins). For larger fields, the GMR saturated and a slightly nonlinear increase in MR with B was observed due to a contribution by the residual amorphous matrix. The anisotropic MR effect (AMR≡LMR-TMR) was negative for all fields and temperatures investigated. By measuring the MR of melt-quenched Fe100-xSix solid solutions with x=15, 18, 20, 25 and 28, the observed AMR could be identified as originating from the FeSi nanograins having a D03 structure. © 2010 Elsevier B.V. All rights reserved.This work was supported by the Hungarian Scientific Research Fund (OTKA) through Grant T 038383 as well as by the Hungarian–Spanish Bilateral Cooperation through Grant TéT E-21/04, moreover by the Spanish Government and EU FEDER (Project MAT 2007-65227) and the PAI of the Regional Government of Andalucía (Project P06-FQM-01823). The authors thank Dr. A. Rodriguez Pierna (E.U.I.T.I. of San Sebastian, University of the Basque Country, Spain) for kindly providing the original amorphous Fe63.5Cr10Nb3Cu1Si13.5B9 alloy ribbon. M.C. is grateful to the European Commission for financial support under a Marie Curie Intra-European Fellowship for Career Development.Peer Reviewe