Contactless measurement of giant magnetoresistance in CoAg granular films using infrared transmission spectroscopy

• Published in: Journal of applied physics 1999-04, Vol.85 (8), p.5045-5047
• Main Authors: Gester, M., Schlapka, A., Pickford, R. A., Thompson, S. M., Camplin, J. P., Eve, J. K., McCash, E. M.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.370086

A new technique is presented for studying spin dependent transport properties in mesoscopic magnetic structures which exploits the magnetorefractive effect (MRE). A Fourier transform infrared spectrometer was used to measure the MRE of CoAg granular films deposited on thinned Si(001) substrates. Infrared transmission spectra were recorded over a wavelength range from 2.5 to 18.2 μm in an applied magnetic field up to 1.5 kOe. The resulting relative transmission curves have a minimum at approximately 7 μm which deepens if the applied magnetic field is increased. This behavior can be described by model calculations in the self-averaging limit from which the scattering rates can be extracted when fitted to the experimental spectra. The field dependent behavior of the MRE reproduces the magnetoresistance behavior measured using a conventional four-point probe demonstrating the capability of the MRE to study magnetotransport without making electrical contacts.