Giant ΔE effect and magnetomechanical coupling factor in amorphous Fe80P13C7ribbons

The magnetomechanical coupling factor k, the Young\´s modulus and the effect as a function of bias field were measured by a mechanical resonance method of amorphous Fe80P13C7ribbons which were annealed at different temperatures in a magnetic field. In the ribbon which was annealed at 350°C for 20 minutes, a remarkably large coupling factor k was found in the bias field 5 Oe to be 0.53, which was almost the same as the value of the high magnetostrictive rare earth-Fe2. The effect increased with the increase of the bias field, took a gigantic value 0.8 at about 5 Oe and then decreased monotonically with the increase of the bias field. The effect is known to correspond to a change in sound velocity, so that the change of the sound velocity was also observed as a function of the frequency from 100kHz to 1MHz in a delay line using the ribbons.