Anomalous and planar Hall effects in Co1−xHox thin films across the magnetic sublattice compensation temperature

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 the anisotropic magnetoresistance (Δρxx), planar Hall effect (ρxyPHE), and anomalous Hall effect (ρxyAHE) is reported on a series of Co1−xHox thin films over a wide field–temperature (H–T) phase space. Close to the magnetic compensation temperature, the ρxyAHE–H loops show a double sign reversal and signatures of spin-flop transition at higher fields. The Δρxx and ρxyPHE also display strong deviations from the classical angular dependence seen in soft ferromagnets like permalloy as the angle ϕ between in-plane current and magnetic field is scanned from 0 to 2π. 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 the 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.