Magnetoresistance and magnetic force microscopy studies in Ni80Fe20 disk- and ring-patterned wires

Abstract

We have investigated the magnetization reversal process of the disk-, ring-, and center dot ring-patterned Ni80Fe20 wires. For the fields applied perpendicular to the wire direction, interesting shape dependent magnetoresistance (MR) ratios were found. The MR ratios were varied from 0.8%, 0.65%, and 0.4% at room temperature and 1.7%, 1.5%, and 1.1% at 10 K for the disk-, ring-, and center dot ring-patterned wires. For the same wires, the switching field is reduced from −170, −110, and −90 Oe at room temperature to −140, −70, and −20 Oe at 10 K. These results were due to the shape anisotropy and domain-wall motion. The anisotropy MR (AMR) ratios measured at 10 K of the disk-, ring-, and center dot ring-patterned wires were 1.9±0.1%, 1.7±0.1%, and 1.3±0.1%, respectively, it is almost even the same (1.1±0.1%) at room temperature. We have observed that the center dot reduces the MR ratio and increases magnetic saturation field of the nanosize Ni80Fe20 wires.

Investigation of magnetization reversal in chains of permalloy ellipses via magnetoresistance measurement and magnetic force microscopy

“…A coherent rotation, in which the exchange energy dominates the system, is the primary reversal process in smaller ellipses with single domain configuration. On the other hand, non-coherent rotation might occur in larger and/or connected ellipses and dots [7][8][9][10][11][12][13]. Herein, we study the size dependent magnetization reversal properties in single and chained permalloy ellipses to demonstrate the assorted switching mechanisms.…”