Influence of Ferromagnetic Interlayer Exchange Coupling on Current-induced Magnetization Switching and Dzyaloshinskii-Moriya Interaction in Co/Pt/Co Multilayer System

TL;DR

This study explores how interlayer exchange coupling and Dzyaloshinskii-Moriya interaction influence multilevel magnetization switching in Co/Pt/Co multilayers, combining experiments and simulations to understand the underlying mechanisms for potential storage device applications.

Contribution

It provides new insights into the interplay between IEC, DMI, and magnetization dynamics in Co/Pt/Co systems, supported by experimental measurements and numerical modeling.

Findings

Four resistance states observed under magnetic field and spin current.

Interlayer coupling affects DMI and magnetization switching behavior.

Magnetic domain imaging supports the proposed mechanisms.

Abstract

This paper investigates the relationship among interlayer exchange coupling (IEC), Dzyaloshinskii-Moriya interaction (DMI), and multilevel magnetization switching within a Co/Pt/Co heterostructure, where varying Pt thicknesses enable control over the coupling strength. Employing Brillouin Light Scattering to quantify the effective DMI, we explore its potential role in magnetization dynamics and multilevel magnetization switching. Experimental findings show four distinct resistance states under an external magnetic field and spin Hall effect related spin current. We explain this phenomenon based on the asymmetry between Pt/Co and Co/Pt interfaces and the interlayer coupling, which, in turn, influences DMI and subsequently impacts the magnetization dynamics. Numerical simulations, including macrospin, 1D domain wall, and simple spin wave models, further support the experimental observations of multilevel switching and help uncover the underlying mechanisms. Our proposed explanation, supported by magnetic domain observation using polar-magnetooptical Kerr microscopy, offers insights into both the spatial distribution of magnetization and its dynamics for different IECs, thereby shedding light on its interplay with DMI, which may lead to potential applications in storage devices.