Influence of Aspect Ratio on Giant Magnetoimpedance Effect for Fe 67 Co 18 Si 11 B 4 Amorphous Ribbons

The effect of sample geometry aspect ratio ( l/w ) on the giant magnetoimpedance (GMI) in Fe 67 Co 18 Si 11 B 4 amorphous ribbons was investigated systematically. The GMI profiles were measured as a function of the external magnetic field at different frequencies up to 110 MHz. The results show that there exists a critical aspect ratio (( l/w ) 0 = 5.4) below which the maximum GMI effect and sensitivity η decrease with decreasing l/w and above which the maximum GMI effect keeps almost constant and η decreases with increasing l/w . The observed dependence on aspect ratio as ( l/w ) < ( l/w ) 0 is correlated with the magnetization process: Complex domain structures emerged near the ribbon ends to decrease the magnetostatic energy, modify the transverse permeability and consequently GMI response. Contributions from transverse permeability and resistance may dominantly determine the change of GMI effect as ( l/w ) > ( l/w ) 0 .