Direct experimental evidence of an anomalous segregation in - granular alloys and its influence on magnetoresistance

M. L. Fdez-Gubieda; A. García Prieto; A. García-Arribas; C. Meneghini; S. Mobilio

doi:10.1209/epl/i2002-00121-4

All issues

Volume 59 / No 6 (September II 2002)

Europhys. Lett., 59 6 (2002) 855-861

Abstract

Issue		Europhys. Lett. Volume 59, Number 6, September II 2002


Page(s)		855 - 861
Section		Condensed matter: structure, mechanical and thermal properties
DOI		https://doi.org/10.1209/epl/i2002-00121-4
Published online		01 September 2002

Europhys. Lett., 59 (6), pp. 855-861 (2002)

Direct experimental evidence of an anomalous $\chem{Co}$ segregation in $\chem{Co}$ - $\chem{Cu}$ granular alloys and its influence on magnetoresistance

M. L. Fdez-Gubieda¹, A. García Prieto¹, A. García-Arribas¹, C. Meneghini²^,3 and S. Mobilio⁴^,3

¹ Departamento de Electricidad y Electrónica, Universidad del País Vasco Apartado 644, E-48080 Bilbao, Spain
² Istituto Nazionale di Fisica della Materia (INFM), c/o ESRF GILDA CRG B.P. 220, F-38043 Grenoble, France
³ Dipartimento di Fisica “E. Amaldi”, Università di Roma Tre Via della Vasca Navale 84, I-00146 Roma, Italy
⁴ Laboratori Nazionali di Frascati (INFN) - P.O. Box 13, I-00044 Frascati, Italy

Received: 14 January 2002
Accepted: 1 July 2002

Abstract

In $\chem{Co}$ - $\chem{Cu}$ metastable alloys, suitable thermal treatments create $\chem{Co}$ nanoclusters that are responsible for the giant magnetoresistance phenomena. A detailed microscopic study by means of high-resolution X-ray diffraction and extended X-ray absorption spectroscopy has revealed an anomaly in the thermally induced segregation process, occurring at the same temperature regardless of the sample composition. This phenomenon roughens the nanocluster interface and degrades the sample magnetotransport properties.

PACS: 61.46.+w – Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals / 61.10.Ht – X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc / 75.70.Pa – Giant magnetoresistance

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