Magnetostriction of permalloy epitaxial and polycrystalline thin films

Abstract

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 ʎs = 5 × 10–6, 4 × 10–6, 3 × 10–6, and 6 × 10–6 for the (111), the (100), the (110) epitaxial and the polycrystalline films, respectively.