Quantification of Mixed Bloch-Néel Topological Spin Textures Stabilized by the Dzyaloshinskii-Moriya Interaction in Co/Pd Multilayers

Abstract

The three-dimensional structure of nanoscale topological spin textures stabilized by the Dzyaloshinskii-Moriya interaction is governed by the delicate competition between the exchange, demagnetization, and anisotropy energies. The quantification of such spin textures through direct experimental methods is crucial towards understanding the fundamental physics associated with their ordering, as well as their manipulation in spintronic devices. Here, we extend the Lorentz transmission electron microscopy technique to quantify mixed Bloch-Néel chiral spin textures stabilized by the Dzyaloshinskii-Moriya interaction in Co=Pd multilayers. Analysis of the observed intensities under varied imaging conditions coupled to corroborative micromagnetic simulations yields vital parameters that dictate the stability and properties of the complex spin texture, namely, the degree of mixed Bloch-Néel character, the domain wall width, the strength of the Dzyaloshinskii-Moriya interaction, and the exchange stiffness. This approach provides the necessary framework for the application of quantitative Lorentz phase microscopy to a broad array of topological spin systems.

Scaling, rotation, and channeling behavior of helical and skyrmion spin textures in thin films of Te-doped Cu 2 OSeO 3

“…Skyrmions, i.e., smooth and topologically stable spin textures with a nontrivial topology (1, 2), potentially offer notable advancement for the regime of next-generation electronics (3,4), spintronics (5), and condensed matter physics (6)(7)(8)(9)(10). Magnetic skyrmions have been reported in several chiral magnetic single crystals (11)(12)(13), polycrystalline alloys (14), multilayered thin films (15)(16)(17)(18), and multiferroics (19,20) and are envisaged as potential candidates for high-density racetrack memories (21), cache memory (22), ultralow energy spintronic switches (23), and skyrmion reshufflers for probabilistic computing (24). For the realization of these potential applications, the energy efficient creation, annihilation, and controlled manipulation of skyrmion lattices (SkLs) (5,25,26) in designed architectures are essential.…”

Stabilizing chiral spin structures via an alternating Dzyaloshinskii-Moriya interaction

“…To compensate for this, the magnetic volume is usually increased to enhance the thermal stability and reduce the skyrmion energy [12][13][14]18]. The concomitant increase of dipolar interactions, however, has been shown both theoretically and experimentally to compete with the DMI, leading to a nonuniform magnetic chirality across the thickness of the layers [19][20][21][22][23][24][25][26][27][28]. This is considered detrimental for applications because most of the functionality relies on the uniform chirality of a skyrmion across the thickness of the multilayer system [29].…”

Magnetic Skyrmions: Theory and Applications

“…The in-plane component of the magnetization, in the Néel skyrmion, is always pointed in the radial direction [34], while it is oriented perpendicularly with respect to the position vector in the Bloch skyrmion [26]. Different from these two well-known types of skyrmions are skyrmions with mixed Bloch-Néel topological spin textures observed in Co/Pd multilayers [35]. Magnetic antiskyrmions, having a more complex boundary compared to the chiral magnetic boundaries of skyrmions, exist above room temperature in tetragonal Heusler materials [36].…”