Nonreciprocal spin wave in room-temperature van der Waals ferromagnet $(\rm Fe_{0.78}Co_{0.22})_{5}GeTe_{2}$

TL;DR

This study demonstrates nonreciprocal spin wave behavior in room-temperature van der Waals ferromagnet $(\rm Fe_{0.78}Co_{0.22})_{5}GeTe_{2}$, highlighting the role of Dzyaloshinskii-Moriya interaction and potential for spintronic applications.

Contribution

It reveals the presence of bulk Dzyaloshinskii-Moriya interaction in Co-doped Fe5GeTe2 and characterizes its impact on spin wave nonreciprocity at room temperature.

Findings

Nonreciprocal spin wave observed in thick flakes.

Bulk DMI parameter D measured as 0.08 mJ/m^2.

Co-doping enhances DMI compared to pure Fe5GeTe2.

Abstract

Here, we investigate the spin waves in room-temperature van der Waals ferromagnet $(\rm Fe_{0.78}Co_{0.22})_{5}GeTe_{2}$ by utilizing Brillouin light scattering technique. The spin wave dispersion in flakes of different thicknesses shows the key role of dipolar interaction in the spin waves of vdW ferromagnets, and the non-reciprocity of spin wave in thick flakes is observed, which is attributed to the bulk Dzyaloshinskii-Moriya interaction after excluding the influence of dynamic dipolar interaction. The measured bulk DMI parameter D is 0.08 $\rm mJ/m^2$, which is double that of pure $\rm Fe_5GeTe_2$. Our work shows that Co-doped $\rm Fe_5GeTe_2$ is a promising platform for investigating propagating spin wave and topological spin textures at room temperature.