Influence of heavy metal materials on magnetic properties of Pt/Co/heavy metal tri-layered structures

TL;DR

This study systematically investigates how different heavy metal capping layers affect the magnetic properties of Pt/Co/HM tri-layered structures, revealing the role of interfacial effects in magnetic anisotropy and damping.

Contribution

It provides the first systematic experimental analysis of how W, Ta, and Pd capping layers influence magnetic properties in Pt/Co/HM structures, highlighting the importance of interfacial interactions.

Findings

W capping layer results in the lowest damping constant

Interfacial hybridization significantly affects magnetic anisotropy

Different heavy metals alter spin-orbit coupling and magnetic damping

Abstract

Pt/Co/heavy metal (HM) tri-layered structures with interfacial perpendicular magnetic anisotropy (PMA) are currently under intensive research for several emerging spintronic effects, such as spinorbit torque, domain wall motion, and room temperature skyrmions. HM materials are used as capping layers to generate the structural asymmetry and enhance the interfacial effects. For instance, the Pt/Co/Ta structure attracts a lot of attention as it may exhibit large Dzyaloshinskii-Moriya interaction. However, the dependence of magnetic properties on different capping materials has not been systematically investigated. In this paper, we experimentally show the interfacial PMA and damping constant for Pt/Co/HM tri-layered structures through time-resolved magneto-optical Kerr effect measurements as well as magnetometry measurements, where the capping HM materials are W, Ta, and Pd. We found that the Co/HM interface plays an important role on the magnetic properties. In particular, the magnetic multilayers with a W capping layer features the lowest effective damping value, which may be attributed to the different spin-orbit coupling and interfacial hybridization between Co and HM materials. Our findings allow a deep understanding of the Pt/Co/HM tri-layered structures. Such structures could lead to a better era of data storage and processing devices.