Dipolar magnetic interactions among magnetic microwires

This paper presents a brief review of experiments and simulations on dipole-dipole interacting magnetic microwires that form a linear chain. In particular, recent studies on (a) amorphous Fe77.5Si7.5B15 and (b) granular Cu45Ni25Co29Mn1 microwires are discussed. Hysteresis loops were performed at room temperature for an array of N microwires (N = 1-5 for (a) and N = 1-100 for (b)) and compared with Monte Carlo simulations. In the case of amorphous soft magnetic materials (a), clear steps and plateaux on the demagnetization are visible, each step corresponding to the magnetization reversal of an individual wire. In the case of CuNiCoMn microwires (b), that exhibit a granular structure and a nearly superparamagnetic behavior when isolated, it was found that the coercivity abruptly changes from 20 to 700 Oe for N around 10. Novel Monte Carlo simulations are presented, providing useful insights about the effect of long-range interactions that account for the interesting observed magnetic behaviors. (C) 2002 Elsevier Science B.V. All rights reserved.