Magnetic and transport properties of Fe-rich thin cold-drawn amorphous wires

Electrical resistivity, magnetic (saturation magnetization and switching field of the magnetic bistability) and magnetoimpedance measurements are reported in cold-drawn amorphous Fe77.5B15Si7.5 thin wires of 14 μm diameter. Such measurements have been performed in the thin wire treated by current annealing. Electrical resistivity dependence with the intensity of the current flowing along the thin wire shows a deep decrease around 70 mA ascribed to the crystallization process. Dependence curve of the magnetization with the intensity of the current presents a change of slope at 40 mA which is ascribed to the nucleation of grains. Unusual dependence of switching field on applied stress exhibits a decrease of the switching field with the external stress in the as-prepared cold-drawn and post-treated thin wire. Magnetoimpedance ratio evolves from one to two peaks response increasing the frequency. Observed dependences interpreted taking into account strong internal stresses induced by the cold-drawn process.