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تسجيل مستخدم جديدAnisotropic Dzyaloshinskii-Moriya Interaction in ultra-thin epitaxial Au/Co/W(110)
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We have used Brillouin Light Scattering spectroscopy to independently determine the in-plane Magneto-Crystalline Anisotropy and the Dzyaloshinskii-Moriya Interaction (DMI) in out-of-plane magnetized Au/Co/W(110). We found that the DMI strength is 2-3 times larger along the bcc$[bar{1}10]$ than along the bcc$[001]$ direction. We use analytical considerations to illustrate the relationship between the crystal symmetry of the stack and the anisotropy of microscopic DMI. Such an anisotropic DMI is the first step to realize isolated elliptical skyrmions or anti-skyrmions in thin film systems with $C_{2v}$ symmetry.
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We studied the symmetry of magnetic properties and the resulting magnetic textures in ultra-thin epitaxial Au$_{0.67}$Pt$_{0.33}$/Co/W, a model system exhibiting perpendicular magnetic anisotropy and interface Dzyaloshinskii-Moriya interaction (DMI).
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We have studied the Co layer thickness dependences of magnetocrystalline anisotropy (MCA), Dzyaloshinskii-Moriya interaction (DMI), and orbital moment anisotropy (OMA) in W/Co/Pt trilayers. We find the MCA favors magnetization along the film normal a
nd monotonically increases with decreasing effective magnetic layer thickness ($t_mathrm{eff}$). The magnitude of the Dzyaloshinskii-Moriya exchange constant ($|D|$) increases with decreasing $t_mathrm{eff}$ until $t_mathrm{eff} sim$1 nm, below which $|D|$ decreases. MCA and $|D|$ scale with $1/t_mathrm{eff}$ for $t_mathrm{eff}$ larger than $sim$1.0 nm, indicating an interfacial origin. To clarify the cause of the $t_mathrm{eff}$ dependences of MCA and DMI, the OMA of Co in W/Co/Pt trilayers is studied using x-ray magnetic circular dichroism (XMCD). We find non-zero OMA when $t_mathrm{eff}$ is smaller than $sim$0.8 nm. The OMA increases with decreasing $t_mathrm{eff}$ at a rate that is larger than what is expected from the MCA and Brunos formula, indicating that other factors contribute to the MCA at small $t_mathrm{eff}$ to break the $1/t_mathrm{eff}$ scaling. The $t_mathrm{eff}$ dependence of the OMA also suggests that $|D|$ at $t_mathrm{eff}$ smaller than $sim$1 nm is independent of the OMA at the interface. We consider the growth of Co on W results in a strain that reduces the interfacial MCA and DMI at small $t_mathrm{eff}$, indicating the importance of lattice structure to control their properties.
The Dzyaloshinskii-Moriya interaction (DMI), being one of the origins for chiral magnetism, is currently attracting huge attention in the research community focusing on applied magnetism and spintronics. For future applications an accurate measuremen
t of its strength is indispensable. In this work, we present a review of the state of the art of measuring the coefficient $D$ of the Dzyaloshinskii-Moriya interaction, the DMI constant, focusing on systems where the interaction arises from the interface between two materials. The measurement techniques are divided into three categories: a) domain wall based measurements, b) spin wave based measurements and c) spin orbit torque based measurements. We give an overview of the experimental techniques as well as their theoretical background and models for the quantification of the DMI constant $D$. We analyze the advantages and disadvantages of each method and compare $D$ values in different stacks. The review aims to obtain a better understanding of the applicability of the different techniques to different stacks and of the origin of apparent disagreement of literature values.
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