Structural and magnetoresistive properties of mechanically alloyed Fe-Co-Ag

• Published in: Journal of physics. Condensed matter 1999-11, Vol.11 (45), p.8839-8853
• Main Authors: Cohen, Neil S, Pankhurst, Quentin A, Barquín, Luis Fernández
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic conduction in metals and alloys; Electronic transport in condensed matter; Exact sciences and technology; Fine-particle systems; Galvanomagnetic and other magnetotransport effects; Magnetic properties and materials; Metals. Metallurgy; Physics; Small particles and nanoscale materials; Studies of specific magnetic materials
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/11/45/308

The structural, magnetic and magnetoresistive properties of a wide range of mechanically alloyed Fe-Co-Ag granular materials were investigated by means of x-ray diffraction, Mossbauer spectroscopy, differential scanning calorimetry, DC magnetometry and magneto-resistance measurements. Binary Fe-Co alloys, milled using Syalon containers, showed a mixed fcc-bcc structure for Fe compositions between 20 and 25 at.%. The ternary alloys were found to comprise dispersions of Fe-Co grains in an fee silver matrix, with the structure and magnetic properties of the Fe-Co grains mirroring those of the corresponding binary Fe-Co alloys. For materials with Fe:Co ratios in the region of the mixed fcc-bcc phases, additional components were noted in their Mossbauer spectra (a secondary sextet and a paramagnetic doublet, accounting for up to 63% of the spectral area), indicating the intermixing of a significant number of small Fe- Co clusters or fine grains into the Ag matrix. Alloys in this region were also found to have the largest magnetoresistive responses, with the maximum being a 5.8% effect in (Fe sub 0.15 Co sub 0.85 ) sub 30 Ag sub 70 , as measured at 10 K in afield of 3 T. This indicates the dominant significance of fine grain intermixing in these alloys. (38 samples of varying composition.)