Generation of large Barkhausen jump in bilayered thin film

A pulse voltage of half-amplitude width of approximately 20 /spl mu/s was induced in a detecting coil wound around a wire by large Barkhausen effect, when torsional stress and AC external magnetic field were applied to Fe-Co-V fine wires. Effective characteristics of the pulse voltage, the pulse amplitude and the pulse width were found not depend on frequency of external magnetic field. Based on this phenomenon, a unique magnetic sensor was developed for a flow meter. In this study, the bilayered thin films with several different coercive forces and residual stresses were fabricated in order to simulate the Barkhausen effect in the thin film. As a result we observed a large Barkhausen jump in the bilayered film having the upper layer in tension and the lower layer in compression. The induced pulse voltages are not dependent on the external magnetic field frequency.