Remnant magnetoresistance and hard-axis collapse in Co thin films
Phys. Rev. B 113, 064428 – Published 18 February, 2026
DOI: https://doi.org/10.1103/7tdb-mbbt
Abstract
We present magnetization and magnetoresistance measurements obtained on Co thin films with collapsed hard-magnetization axes—a presence of sharp peaks in the angular variations of the remnant magnetization and the coercivity, centered 90 degrees off of the easy axis. A clear correlation between these peaks and the singularities observed in the respective angular remnant magnetoresistance variations is identified. We reveal, with the aid of a model developed here, that there is only an anisotropic magnetoresistance contribution to the remnant magnetoresistance of our films. These results strongly support the presumption that systems with collapsed hard axes consist of grains with two slightly misaligned easy axes. While at saturation each of them behaves as a monodomain, at remanence it splits up in two domains, relative to the two local easy axes. Unlike previous conjectures, our results corroborate with the hypothesis that these domains coexist for all in-plane magnetic field orientations and not only for in collapse region. Whereas in the latter the two domains form scissorlike configurations, these form a small angle, which varies in an undulatory manner with the field orientation.
