Gamma Irradiation Effect on Asymmetric Giant Magnetoimpedance of Co68.15Fe4.35Si12.5B15 Amorphous Alloy

The giant magneto impedance (GMI) effect is a large variation in the electrical impedance of a magnetic conductor when subjected to a static magnetic field. The sensitivity to the direction (AGMI) and magnitude of applied  magnetic field    and also linearity levels   of this  effect are three important parameters in magnetic sensors application. A suitable annealing procedure can be used to achieve an optimum response of GMI by reducing the quenched-in internal stresses and induces transverse magnetic anisotropy.  In this research the effect of irradiation of gamma rays from two gamma sources (60Co, 137Cs) on the asymmetry of GMI  of Co68.15Fe4.35Si12.5B15  amorphous alloy is studied. The optimum asymmetry of studied sample obtained after 30 (24) hours irradiation by photons emitted by 60Co (137Cs) source. The X-ray diffraction pattern shows a transition from amorphous phase to a crystalline phase in  samples. Results  show that induced changes by irradiation with 137Cs source leads to a better sensitivity  to  direction of applied magnetic field especially in case of irradiated sample for 24 hours. This sample can be considered a good magnetic sensor candidate.