Magnetic structure study in thin films by polarized neutron reflectometry

DAFNE GOIJMAN; JAVIER E. GÓMEZ; MARIANO PAULIN; EMILIO DE BIASI; ALEXEI VOROBIEV; FRÉDÉRIC OTT; ALEJANDRO BUTERA; JULIAN MILANO

Conferencia; International Conference on Neutron Scattering 2022; 2022

Ferromagnetic thin films with perpendicular magnetic anisotropy (PMA) have attractedmuch attention due to their potential application in the field of magnetic recording, logic,and memory devices. This kind of material exhibits a magnetic domain structure in the form of thin parallel stripes which occurs only above critical thickness. The PMA can havedifferent origins but is mostly determined by magnetocrystalline, magnetoelastic, orinterfacial contributions. Magnetization of thin films can be studied in a limited way withconventional laboratory magnetometric techniques. However, polarized neutronreflectometry (PNR) is an excellent tool to study details of magnetic configuration incomplex structures and multilayers due to the magnetic coupling between the neutron andthe magnetic moments of the material. As the neutron scattering is sensitive only to the inplane component of magnetization, one may determine from the PNR data the profile of this component along with the depth of the film structure.In this work, we have studied FePt and Permalloy thin films with different thicknesses. Toobtain the magnetic depth profile, we have performed PNR measurements at roomtemperature in different states of magnetization. The measurements were carried out with amagnetic field of 3000G (saturation state), 600G, 200G, and 26G (close to remanencestate). The experiments were performed in PRISM at The Laboratoire Léon Brillouin(Saclay) and in SuperADAM at The Institut Laue-Langevin (Grenoble) in France. The results were compared with micromagnetic simulations.