Uniaxial Magnetic Anisotropy in Evaporated Films Caused by the Interaction with Substrate

Abstract

A contribution to the magnetic anisotropy of evaporated films by an anisotropic mechanical stress caused by the substrate has been examined. Ni, Co, 85%Ni–Fe alloy with negative magnetostriction and 54%Fe–Co alloy with positive magnetostriction are evaporated onto X-and Z-cut quartz, and glass substrates. An anomalously large uniaxial magnetic anisotropy of 104∼105 ergs/cc compared to the induced anisotropy by magnetic annealing was found in all films deposited onto X-cut quartz substrates, while no anisotropy was found for the films deposited onto Z-cut quartz and glass. The direction of the easy axis and the value of the anisotropy are explained with the magneto-elastic coupling effect caused by the difference between the isotropic thermal expansion of films and the anisotropic expansion of the X-cut quartz substrate.