Angular Remanence and Anisotropy Orientation Distribution in Nickel Films on LiNbO3

Nickel thin films (100 nm) deposited on
$128^{\circ } Y$
-cut: LiNbO
₃
exhibits a well-defined, uniaxial, magnetic anisotropy after annealing at 325 °C. Simulating the magnetization of these films using a temperature-dependent Stoner–Wohlfarth (SW) model indicates that the films have a very narrow angular distribution of anisotropy axis orientations. Here, we report a direct measurement of the angular distribution of anisotropy orientation by measuring the angular remanence after magnetic saturation. When magnetized to saturation in any direction away from the hard axis, these samples remain nearly uniformly magnetized, with the easy axis remnant magnetization very close to the saturation magnetization (>
$0.97M_{S}$
). When the angle (
$\alpha$
) between the saturating field and the hard axis is
$\vert \alpha \vert < 1$
°, the easy axis remanence drops dramatically, indicating that the sample is no longer uniformly magnetized and has broken up into domains. When magnetized on the hard axis, the easy axis remanence approaches zero. The angular range over which the easy axis remanence drops significantly is a measure of the angular distribution of the anisotropy axes. The full-width at half-maximum (FWHM) of the easy axis remanence as a function of angle
$(\alpha)$
is approximately 0.44° for annealed nickel thin films on
$128^{\circ } Y$
-cut: LiNbO
₃
. The angular remanence is modeled numerically, assuming an ensemble of SW particles with a distributed anisotropy orientation. The magnetic domain structure of the films is confirmed by magneto-optic Kerr effect imaging.