A high sensitive longitudinally driven giant magnetoimpedance of FeCo-based ribbon in weak magnetic field

In this article, a high sensitive longitudinally driven giant magneto-impedance (LDGMI) effect in Fe₃₆Co₃₆Nb₄Si_4.8B_19.2 (FeCo-based) ribbon under weak magnetic field (WMF) was presented. The FeCo-based amorphous ribbon was prepared by single roller quench and annealed with joule-heat in flowing nitrogen atmosphere. The LDGMI effect profiles of FeCo-based ribbon have been measured with HP4294A impedance analyzer. The result shows that the LDGMI effect of FeCo-based ribbon responds to the WMF sensitively (as high as 1380 %/A·m-1). The super high sensitivity can be obtained in a moderate narrow range of annealing current density (27~34 A/mm²) and closely depends on the driven current frequency. The highest sensitivity (1380 %/A·m-1) was observed when the FeCo-based amorphous ribbon annealed at 32 A/mm² for 10 minutes and then driven with AC at the frequency of 300 kHz. The high sensitive LDGMI effect in WMF may results from the multiple magnetic anisotropy structure which induced by the temperature grads in the ribbon. This high sensitive LDGMI effect in WMF is promising for the development of weak magnetic-field sensors.