Anomalous and Planar Hall Effects in Cobalt-Holmium Thin Films Near Magnetic Sublattice Compensation

TL;DR

This study investigates the complex magnetotransport phenomena in CoHo thin films near magnetic compensation, revealing unique Hall effects, anisotropic magnetoresistance deviations, and magnetic domain structures linked to Ho ions' orbital angular momentum.

Contribution

It provides a detailed analysis of Hall effects and magnetoresistance in CoHo thin films near compensation, highlighting the role of Ho ions and magnetic textures, which is novel in ferrimagnetic thin films.

Findings

Double sign reversal in AHE loops near compensation

Strong deviations in AMR and PHE angular dependence

Formation of stripe and bubble magnetic domains

Abstract

Metallic amorphous ferrimagnets derived from alloying 3d transition metals with 4f electron rare earths host fascinating effects of compensation between the 3d and 4f magnetic sublattices. Here, a detailed study of anisotropic magnetoresistance (AMR), planar Hall effect (PHE) and anomalous Hall effect (AHE) are reported on a series of CoHo thin films over a wide field temperature phase space. Close to magnetic compensation temperature, the AHE loops show a double sign reversal and signatures of spin flop transition at higher fields. The AMR and PHE also display strong deviations from the classical angular dependence seen in soft ferromagnets like permalloy as the angle between in-plane current and magnetic field is scanned from 0 to 360 degrees. It is argued that the non zero orbital angular momentum of Ho ions in the lattice and stabilization of bubble domains below magnetic saturation may be responsible for such features. Direct imaging of magnetic textures with X ray photoelectron microscopy shows formation of stripe domain patterns in the regime of sublattice compensation. Such stripes are likely to transform into magnetic bubbles before full saturation is reached in a large magnetic field.