The impact of a magnetic field on ferromagnetic materials isolated using ultraviolet laser ablation

Abstract

Laser ablation technology is used to isolate magnetic material to generate a local magnetic field effect. The impact of an induced magnetic field is enhanced by using the external magnetic field and can be widely employed to collect magnetic particles and position biomolecular in the bio-examination field. In addition, the magnetic field is affected and induced by the thermal stress produced after energy is exerted on the materials. Therefore, this study presents the phase of induced magnetic field (PIMF) of ferromagnetic film (Ni—1-μm thick) isolated using a 355-nm pulsed ultraviolet laser. In the experiment, three patterns comprising the following shapes and various isolated angle were designed for testing: hexagon (type I, 120°), L shape (type II, 90°), and cross shape (type III, 90°). The magnetic force microscopy image showed that when the isolating angle decreased, the PIMF increased, the value of which at the periphery of the corner of the type I and II patterns was −3.96° and −4.09°, respectively. In addition, by increasing the ablation time and residual thermal stress remaining in the material to increase the impact of the material’s properties when laser scanning speed was reduced from 1,000 to 500 mm/s, the PIMF value increased from −4.09° to −5.82°. The PIMF value of the type III pattern increased to −9.87° because the residual thermal stress was twice that of the type II pattern. In the future, the experimental results can be used as a helpful reference for controlling magnetic particles in biomedical chips.