Tuning Dzyaloshinskii-Moriya interaction in ferrimagnetic GdCo: A first-principles approach

Abstract

We present a systematic analysis of our ability to tune chiral Dzyaloshinskii-Moriya interaction (DMI) in compensated ferrimagnetic $\mathrm{Pt}/\mathrm{GdCo}/{\text{Pt}}_{1\ensuremath{-}x}{\text{W}}_{x}$ trilayers by cap layer composition. Using first-principles calculations, we show that the DMI increases rapidly for only $\ensuremath{\sim}10$% W and saturates thereafter, in agreement with experiments. The calculated DMI shows a spread in values around the experimental mean, depending on the atomic configuration of the cap layer interface. The saturation is attributed to the vanishing of spin-orbit coupling energy at the cap layer and the simultaneous constancy at the bottom interface. Additionally, we predict the DMI in $\mathrm{Pt}/\mathrm{GdCo}/X$ $(X=\text{Ta},\text{W},\text{Ir})$ and find that W in the cap layer favors a higher DMI than Ta and Ir that can be attributed to the difference in $d$-band overlap around the Fermi level. Our results open up exciting combinatorial possibilities for controlling the DMI in ferrimagnets towards nucleating and manipulating ultrasmall high-speed skyrmions.