Influence of oxygen ion implantation on magnetic microstructure in Pt/Co/Pt multilayers with perpendicular magnetic anisotropy

TL;DR

This study demonstrates that oxygen ion implantation in Pt/Co/Pt multilayers significantly enhances domain wall velocity and modifies magnetic properties, offering a method to tailor interfaces for advanced spintronic applications.

Contribution

It introduces controlled oxygen ion implantation as a technique to modify magnetic microstructure and improve domain wall dynamics in perpendicular magnetic multilayers.

Findings

DW velocity increased by over 50 times after implantation

Perpendicular anisotropy was lost at high implantation fluence

Structural and magnetic changes lower energy barriers for DW motion

Abstract

The interaction of oxygen with cobalt and cobalt-based alloys has been a very important topic in the field of spintronics as it leads to enhanced orbital anisotropy and interfacial Dzyaloshinskii-Moriya interaction (DMI), which are crucial in the context of applications such as magnetic tunnel junctions (MTJs) based data storage and domain wall (DW) motion. To understand the complex and interesting relationship between oxygen and ferromagnetic (FM)/heavy metal (HM) interfaces, we studied controlled oxygen ion implantation in a cobalt layer located in a Pt/Co 1.2 /Pt (nm) multilayer with a specific structure. At high implantation fluence, the perpendicular anisotropy was lost, as verified by in-plane hysteresis measurements. Under low magnetic field conditions, the DW dynamics of Co/Pt multilayers were analyzed, highlighting key parameters such as DW velocity, roughness amplitude, and roughness exponent. After O+-ion implantation, the DW velocity increased by more than 50 times, rising from 5 um/s to 300 um/s compared with the as-deposited multilayer. The fundamental cause of this improvement is the structural and magnetic changes brought by the implantation, which successfully lower the energy barriers preventing DW movements. The results show how oxygen implantation can be used to precisely tailor the ferromagnetic interfaces, leading to promised improvements in the functionality of next-generation spintronic devices.