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Variation of sign and magnitude of the Dzyaloshinskii-Moriya interaction of a ferromagnet with an oxide interface

2020; American Physical Society; Volume: 101; Issue: 5 Linguagem: Inglês

10.1103/physrevb.101.054421

2469-9977

Monika Arora, Justin M. Shaw, Hans T. Nembach,

ZnO doping and properties

We demonstrate that both the magnitude and sign of the Dzyaloshinskii-Moriya interaction can be tuned by modifying the type and thickness of an oxide layer adjacent to a ferromagnet. We focus on $\mathrm{Ti}/\mathrm{Cu}/\mathrm{C}{\mathrm{o}}_{90}\mathrm{F}{\mathrm{e}}_{10}/\mathrm{Ta}({d}_{\mathrm{Ta}})/\mathrm{Oxide}/\mathrm{Ta}$ structures, where the Ta interlayer thickness ${d}_{\mathrm{Ta}}$ ranged from 0 nm to 3 nm, followed by an exposure to oxygen and ``Oxide'' can mean $\mathrm{CoFe}{\mathrm{O}}_{\mathrm{x}}$ and/or $\mathrm{Ta}{\mathrm{O}}_{\mathrm{x}}$. We used Brillouin light scattering spectroscopy to directly determine the volume-averaged Dzyaloshinskii-Moriya interaction from the nonreciprocity of the spin-wave frequency. The magnitude of the interfacial Dzyaloshinskii-Moriya interaction, ${D}_{\mathrm{DMI}}$, ranges from $\ensuremath{-}0.17$ to $+0.09(\ifmmode\pm\else\textpm\fi{}0.02)\phantom{\rule{0.16em}{0ex}}\mathrm{mJ}/{\mathrm{m}}^{2}$, clearly showing a change in both sign and magnitude, with an increase of Ta interlayer thickness. The modification of the oxide interface allows us to systematically change the hybridization of the $3d\ensuremath{-}\mathrm{CoFe}$ orbitals from $3d\ensuremath{-}5d$ to $3d\ensuremath{-}2p$ and analyze the influence on the Dzyaloshinskii-Moriya interaction. Importantly, we can vary the Dzyaloshinskii-Moriya interaction while maintaining a relatively small value of the damping parameter.