Huge Dzyaloshinskii-Moriya interactions in Re_Co_Pt thin films

TL;DR

This study demonstrates that Re can significantly enhance Dzyaloshinskii-Moriya interactions in Pt/Co/Re thin films, with the potential for nearly doubling DMI compared to existing systems, depending on interface quality and Re thickness.

Contribution

It reveals Re's role in boosting DMI at interfaces and identifies optimal Re thickness and interface conditions for maximizing DMI in multilayer films.

Findings

Re introduces and amplifies DMI at Co interfaces.

Optimal Re thickness maximizes DMI.

Intermixing at Pt/Co reduces DMI significantly.

Abstract

We investigate the magnetization and the Dzyaloshinskii-Moriya interactions (DMI) in Pt/Co/Re thin films in the case of perfect interfaces and upon the introduction of intermixing on both Co interfaces. Calculations were implemented on a series of systems with a varied number of cobalt atomic layers (ALs). Remarkably, the Re is able to introduce a DMI at the interface with cobalt and also, increase the DMI at the Pt/Co interface. We demonstrate that the chiral magnetic multilayer Pt/Co/Re with chiral spin structure can achieve a huge DMI value which is almost double of that attained in the prototype system W/Co/Pt. We study also the DMI as a function of the Re thickness finding the optimal thickness to maximize the DMI. When we include a disorder that cancels a contribution from all first-neighbor Co atoms in the intermixed region, we found out that intermixing at the two interfaces affects the strength of the DMI solely when introduced at the Pt/Co interface where the DMI loses almost half of its value. On the contrary, the mixing at the Co/Re interface has very little or no effect as compared to the case with perfect interfaces. The value of the DMI would be somewhere between the perfect interface case and the totally intermixed case. The realization of such a device should focus on the reduction of the Pt/Co intermixing to realize this huge DMI interaction.