Effect of interfacial intermixing on the Dzyaloshinskii-Moriya interaction in Pt/Co/Pt

TL;DR

This study investigates how sputter-deposition conditions affect interface quality and the Dzyaloshinskii-Moriya interaction in Pt/Co/Pt thin films, revealing that deposition parameters can be tuned to optimize magnetic properties.

Contribution

It demonstrates that deposition temperature and chamber pressure influence interface quality and DMI, providing a method to control magnetic interactions in thin films.

Findings

Interface quality varies with deposition temperature, peaking at 250°C.

Net DMI correlates with differences in top and bottom interface qualities.

DMI increases linearly with temperature at low chamber pressures.

Abstract

We study the effect of sputter-deposition conditions, namely substrate temperature and chamber base pressure, upon the interface quality of epitaxial Pt/Co/Pt thin films with perpendicular magnetic anisotropy. Here we define interface quality to be the inverse of the sum in quadrature of roughness and intermixing. We find that samples with the top Co/Pt layers grown at 250 degrees C exhibit a local maximum in roughness-intermixing and that the interface quality is better for lower or higher deposition temperatures, up to 400 degrees C, above which the interface quality degrades. Imaging the expansion of magnetic domains in an in-plane field using wide-field Kerr microscopy, we determine the interfacial Dzyaloshinskii-Moriya interaction (DMI) in films in the deposition temperature range 100 degrees C to 300 degrees C. The net DMI is linked to the difference in top and bottom Co interface qualities; the net DMI increases as the difference between top and bottom Co interface quality increases. Furthermore, for sufficiently low base pressures, the net DMI increases linearly with the deposition temperature, indicating that fine-tuning of the DMI may be achieved via the deposition conditions.