Strong Enhancement of Spin-Orbit Torques and Perpendicular Magnetic Anisotropy in [Pt0.75Ti0.25/Co-Ni multilayer/Ta]n Superlattices

TL;DR

This paper presents a superlattice structure with enhanced spin-orbit torque and magnetic anisotropy, enabling efficient, low-current magnetization switching suitable for advanced spintronic devices.

Contribution

It introduces a novel [Pt0.75Ti0.25/Co-Ni/Ta]n superlattice with linearly increasing spin-orbit torque and magnetic anisotropy, demonstrating improved properties for spintronic applications.

Findings

Spin-orbit torque efficiency increases linearly with layer repetitions.

Perpendicular magnetic anisotropy is enhanced by over two times.

Achieves deterministic, low-current magnetization switching.

Abstract

We report the development of the [Pt0.75Ti0.25/Co-Ni multilayer/Ta]n superlattice with strong spin-orbit torque, large perpendicular magnetic anisotropy, and low switching current density. We demonstrate that the efficiency of the spin-orbit torque increases linearly with the repetition number n, which is in good agreement with the spin Hall effect of the Pt0.75Ti0.25 being the only source of the spin-orbit torque. Meanwhile, the perpendicular magnetic anisotropy field is also enhanced by more than a factor of 2 as n increases from 1 to 6. The [Pt0.75Ti0.25/(Co/Ni)3/Ta]n superlattice also exhibits deterministic, low-current-density magnetization switching despite the very large layer thicknesses. The combination of the strong spin-orbit torque, perpendicular magnetic anisotropy, and low-current-density switching makes the [Pt0.75Ti0.25/Co-Ni multilayer/Ta]n superlattice a compelling material candidate for ultrafast, energy-efficient, long-data-retention spintronic technologies.