Nonlinear temperature dependence of switching fields in relief-structured Co/Ni_(80)Fe_(20) particles

摘要

The temperature dependence of the switching properties in low sub-μm scale Co/Ni_(80)Fe_(20) particles with different aspect ratios L/w (=1-6, w=0.4 μm) and thicknesses t(=1-5 nm) are investigated using magnetotransport measurements of relief-structured films with giant magnetoresistance. The shape of each particle is a parallelogram with slope angle θ(=0°-60°). The switching field of the particles increased with θ due to the variation of the end-domain configuration. Nonlinear temperature dependence of the switching field was observed, which could be explained by the thermal nucleation theory of the magnetization reversal at below 150 K. The amplitude of the energy barrier height ΔE for the reversal was strongly suppressed by decreasing the thickness of the particles. This degradation of the thermal stability may be caused by the variation of the film morphology by decreasing the thickness.