Giant magnetoresistance in nanogranular magnetsA. Glatz1, I. S. Beloborodov1, 2 and V. M. Vinokur1
1 Materials Science Division, Argonne National Laboratory - Argonne, IL 60439, USA
2 James Franck Institute, University of Chicago - Chicago, IL 60637, USA
received 11 December 2007; accepted in final form 27 March 2008; published May 2008
published online 7 May 2008
We study the giant magnetoresistance of nanogranular magnets in the presence of an external magnetic field and finite temperature. We show that the magnetization of arrays of nanogranular magnets has hysteretic behaviour at low temperatures leading to a double peak in the magnetoresistance which coalesces at high temperatures into a single peak. We numerically calculate the magnetization of magnetic domains and the motion of domain walls in this system using a combined mean-field approach and a model for an elastic membrane moving in a random medium, respectively. From the obtained results, we calculate the electric resistivity as a function of magnetic field and temperature. Our findings show excellent agreement with various experimental data.
75.47.De - Giant magnetoresistance.
75.60.-d - Domain effects, magnetization curves, and hysteresis.
75.75.+a - Magnetic properties of nanostructures.
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