Measurement of interfacial Dzyaloshinskii-Moriya interaction from static domain imaging

Abstract

Perpendicularly magnetized thin films with a strong Dzyaloshinskii-Moriya interaction (DMI) exhibit chiral spin structures such as Néel domain walls and skyrmions. These structures are promising candidates for nextgeneration magnetic memory devices. Determining the magnitude of the DMI accurately is key to engineering materials for such applications. Existing approaches are based on quantities extracted either from magnetization dynamics, which present experimental and theoretical challenges, or from measurements of quasistatic domain spacing, which so far have been analyzed using incomplete models or prohibitively slow micromagnetic simulations. Here, we use a recently developed analytical model of stripe domain widths in perpendicularly magnetized multilayers to extract the DMI from domain images combined with magnetometry data. Our approach is tested on micromagnetically simulated domain patterns, where we achieve a 1% agreement of the extracted DMI with the DMI used to run the simulation. We then apply our method to determine the thickness-dependent DMI in two experimental materials, one with ([Pt(2.5-7.5 nm)/Co 60 Fe 20 B 20 (0.8 nm)/MgO(1.5 nm)] 13) and one without ([Pt(2.5-7.5 nm)/Co(0.8 nm)/Pt(1.5 nm)] 13) inversion symmetry breaking. We discuss the means to obtain realistic error bars with our method. Our results demonstrate that analytical domain spacing analysis is a powerful tool to extract the DMI from technologically relevant multilayer materials.

Temperature dependence of the Dzyaloshinskii-Moriya interaction in ultrathin films

“…We find, as would be expected, that the DMI decreases with temperature due to thermal disorder. The value of the DMI reported here is similar to previous reports on Co systems with Pt interfaces [12,34,35]. Since even highly ordered Co/Ru interfaces only have weak DMI [36], the observed DMI is likely due to the Pt/CoFeB interface.…”

Dynamic Symmetry Breaking in Chiral Magnetic Systems

“…While the iDMI is known to lead to smaller equilibrium domain sizes, a similar relationship between film thickness and equilibrium domain size holds in films with this additional energy term. [ 26 ] For the [Co/Ni/Pt] films discussed here, we observe a transition from relatively large domains to stripe domains when increasing the number of repetitions, N , from 2 to 3 (i.e., within the thin film limit, where the equilibrium domain size decreases exponentially with increasing film thickness). Magnetic reversal via dendritic stripe domains occurs by means of growth from a nucleation site, as the stripe tip curvature (and thus, the stripe width) stays more or less constant while the length of the stripe domains increases to fill the area of the film.…”

Scaling of Dzyaloshinskii-Moriya interaction with magnetization in Pt/Co(Fe)B/Ir multilayers

“…We then mounted each sample in turn in an optical cryostat, cooled to 9 K, and captured an image of the domain pattern at several set temperatures while warming back up to room temperature. Using a similar method to Agrawal et al 20 we extracted the domain period from these images. Briefly: a fast-Fourier transform of the image produces rings at a characteristic wavelength related to the maze domains.…”