Magnetic droplet nucleation with a homochiral Néel domain wall

Abstract

We investigate the effect of the Dzyaloshinskii-Moriya interaction (DMI) on magnetic domain nucleation in a ferromagnetic thin film with perpendicular magnetic anisotropy. We propose an extended droplet model to determine the nucleation field as a function of the in-plane field. The model can explain the experimentally observed nucleation in a Co/Ni microstrip with the interfacial DMI. The results are also reproduced by micromagnetic simulation based on the string model. The electrical measurement method proposed in this study can be widely used to quantitatively determine the DMI energy density. Chiral spin textures, such as a skyrmion and a Néel type magnetic domain wall (DW), which are formed in perpendicularly magnetized ferromagnet (FM)/non-magnet (NM) structures, have attracted considerable attention for future spintronic devices that can perform massive and high-speed data processing with low power consumption [1-7].Lack of structural inversion symmetry with strong spin-orbit coupling at the FM/NM interface results in the Dzyaloshinskii-Moriya interaction (DMI) which results in chirality in spin textures [8][9][10]. In recent years, it has been experimentally demonstrated that skyrmion-like bubble domains can be formed stably at room temperature [11][12] and driven along a magnetic nanowire at a velocity of ~100 m/s [13,14]. In addition, a

Correlation of the Dzyaloshinskii–Moriya interaction with Heisenberg exchange and orbital asphericity

“…The measured H n as a function of H x shows a threshold arising from the DMI as predicted by the extended droplet model 24 (see also Supplementary Note 1 , 2 and Method section for details about the analysis and the measurement). Figures 2a–d show H n / H SW ( H x =0) as a function of H x / H K at various temperatures (a, T =300 K; b, 200 K; c, 150 K and d, 100 K).…”

“…The measured H n values are analysed with the extended droplet model 24 . Since H n is proportional to square of DW energy ( ), the σ DW is a crucial parameter for the nucleation 24 , 30 . In case of the droplet with sizable DMI, DW magnetizations are aligned in the radial direction.…”

“…Note that there is a threshold where the starts to become H x dependent. Our previous report showed that the extended droplet model allows us to estimate the DMI-induced field from the threshold field 24 . In spite of such one-dimensional approximation, we have demonstrated that the fitting gives reliable value of the DMI energy density ( D ).…”

“…Here we discuss the microscopic origin of the interfacial DMI with experimental and theoretical studies as follows: First, we show the temperature dependence of the DMI for a Pt/Co/MgO trilayer, which is one of the standard structures used for the studies of the DMI 7 , 12 , 23 , using the extended droplet model 24 . We find that the DMI increases with decreasing temperature in a range from 300 to 100 K. In general, the electron–phonon interaction promotes thermally induced hopping between nearest neighbours when increasing the temperature 25 .…”

Giant Dzyaloshinskii-Moriya interaction in Rashba superlattices

“…Rashba effect manifests most immediately into a spinsplitting within the k space, and it has been vastly utilized to interpret a number of magnetic phenomena [15][16][17][18], in particular those well understood to originate from the ISB, such as the Dzyaloshinskii-Moriya interaction responsible for exotic magnetic textures such as skyrmions and chiral domain walls, and spin-orbit torque. [19,20]. Figure 2 (a) shows the schematic illustration of the droplet measurement.…”