Controlling Magnetic Configuration in Soft-Hard Bilayers Probed by Polarized Neutron Reflectometry

Published

January 13, 2022

Author(s)

Nan Tang, Jung-Wei Liao, Kai Liu, Siu-Tat Chui, Timothy Ziman, Alexander Grutter

Abstract

Hard/soft magnetic bilayer thin films have been widely used in data storage technologies and permanent magnet applications. The magnetic configuration and response to temperatures and magnetic fields in these composite systems are considered to be highly dependent on the interfacial coupling. However, the intrinsic properties of each of the layers, such as the saturation magnetization and layer thickness, also strongly influence the magnetic configuration. Changing these parameters provides an effective method to design the magnetism in composite magnets. Here, we use polarized neutron reflectometry (PNR) to experimentally probe the interfacial magnetic configurations in hard/soft bilayer thin films: L1₀-FePt/A1-FePt, [Co/Pd]/CoPd, [Co/Pt] /FeNi and L1₀-FePt/Fe. These films were designed with different soft and hard layer thicknesses (t_soft and t_hard) and saturation magnetization (s^soft and _s^hard), respectively. The influences of an in-plane magnetic field (_ip) and temperature (T) are also studied using a L1₀-FePt/A1-FePt bilayer sample. Comparing the PNR results to micromagnetic simulations reveals that the interfacial magnetic configuration is highly dependent on _soft,s^soft and the external factors (_p and T), and has a relatively weak dependence on _ℎrd and ^hard^. Key among these results, for thin _oft, the hard and soft layers are rigidly coupled in the out-of-plane direction, then undergo a transition to relax in-plane. This transition can be delayed to larger t_soft by decreasing ^soft. Understanding the influence of these parameters on the magnetic configuration is critical to designing functional composite magnets for applications.

Citation

APL Materials

Volume

10

Issue

1

Pub Type

Journals

Keywords

neutron

Citation

Tang, N. , Liao, J. , Liu, K. , Chui, S. , Ziman, T. and Grutter, A. (2022), Controlling Magnetic Configuration in Soft-Hard Bilayers Probed by Polarized Neutron Reflectometry, APL Materials (Accessed May 7, 2026)

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