Magnetostriction of permalloy epitaxial and polycrystalline thin films

Permalloy epitaxial films of (111), (100), and (110) orientations and a polycrystalline thin film are prepared. Sinusoidal waveforms of magnetostriction are observed when the polycrystalline and the (111)-oriented epitaxial films are measured under rotating magnetic fields ranging from 10 to 1000 Oe. On the contrary, the (100)- and the (110)-oriented films, respectively, show a triangle waveform and a waveform consisting of a mixture of triangular and sinusoidal shapes under low magnetic fields. The waveform variation is interpreted by considering the magnetization structure of magnetically unsaturated film with an in-plane magnetic symmetry related with the crystallographic orientation. The waveforms deformed from sinusoidal shape vary to sinusoidal with increasing the magnetic field. Magnetically saturated (100)- and (110)-oriented films show sinusoidal waveforms. The saturated magnetostriction values are determined as lambda(s) = 5 x 10(-6), 4 x 10(-6), 3 x 10(-6), and 6 x 10(-6) for the (111), the (100), the (110) epitaxial and the polycrystalline films, respectively.