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oai:recercat.cat:2445/106482025-12-05T14:47:17Zcom_2072_1057col_2072_478821col_2072_478822col_2072_478917

urn:hdl:2445/10648 Tunneling magnetoresistance in Co-ZrO2 granular thin films Hattink, Bart Jan García del Muro y Solans, Montserrat Konstantinović, Zorica Batlle Gelabert, Xavier Labarta, Amílcar Superfícies (Física) Superconductivitat Pel·lícules fines Surfaces (Physics) Superconductivity Thin films Granular films composed of well defined nanometric Co particles embedded in an insulating ZrO2 matrix were prepared by pulsed laser depositon in a wide range of Co volume concentrations 0.15 x 0.43. High-resolution transmission electron microscopy TEM showed very sharp interfaces between the crystalline particles and the amorphous matrix. Narrow particle size distributions were determined from TEM and by fitting the low-field magnetic susceptibility and isothermal magnetization in the paramagnetic regime to a distribution of Langevin functions. The magnetic particle size varies little for Co volume concentrations x 0.32 and increases as the percolation limit is approached. The tunneling magnetoresistance TMR was successfully reproduced using the Inoue-Maekawa model. The maximum value of TMR was temperatureindependent within 50–300 K, and largely increased at low T, suggesting the occurrence of higher-order tunneling processes. Consequently, the tunneling conductance and TMR in clean granular metals are dominated by the Coulomb gap and the inherent particle size distribution. 2009-12-29T11:18:30Z 2009-12-29T11:18:30Z 2006 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Reproducció digital del document publicat en format paper, proporcionada per PROLA i http://dx.doi.org/10.1103/PhysRevB.73.045418 Physical Review B, 2006, vol. 73, núm. 4, p. 045418-1-045418-9 http://dx.doi.org/10.1103/PhysRevB.73.045418 (c) The American Physical Society, 2006 info:eu-repo/semantics/openAccess The American Physical Society Articles publicats en revistes (Física Aplicada)