Magnetization reversal in FePt thin films: Experiments and simulations

TL;DR

This study investigates the magnetization reversal mechanisms in FePt thin films, revealing a transition from two-phase reversal to coherent rotation as film thickness increases, influenced by substrate-induced strains affecting coercivity.

Contribution

The paper combines experiments and simulations to elucidate the thickness-dependent magnetization reversal mechanisms in FePt films, highlighting the role of substrate strains on magnetic properties.

Findings

Reversal mechanism shifts from two-phase to coherent rotation at critical thickness

Substrate strains influence the abnormal coercive field behavior

Temperature dependence of PMA is characterized

Abstract

The competition between shape and perpendicular magnetic anisotropies (PMA) in magnetic thin films gives rise to unusual magnetic behaviors. In ferromagnetic films with moderate PMA the magnetic domain configuration transitions from planar to stripe-like domains above a critical thickness, $t_c$. In this article, we present a detailed study of the magnetization switching mechanism in FePt thin films, where this phenomenon is observed. Using micromagnetic simulations and experiments, we found that below $t_c$ the reversal mechanism is well described by the two-phase model while above this thickness the magnetization within each stripe reverses by coherent rotation. We also analyzed the PMA and its temperature dependence, probing that substrate-induced strains are responsible for the abnormal coercive field behavior observed for FePt films with $t>t_c$.