Abstract
Chiral magnetic interactions induce complex spin textures including helical and conical spin spirals, as well as particle-like objects such as magnetic skyrmions and merons. These spin textures are the basis for innovative device paradigms and give rise to exotic topological phenomena, thus being of interest for both applied and fundamental sciences. Present key questions address the dynamics of the spin system and emergent topological defects. Here we analyse the micromagnetic dynamics in the helimagnetic phase of FeGe. By combining magnetic force microscopy, single-spin magnetometry and Landau–Lifschitz–Gilbert simulations we show that the nanoscale dynamics are governed by the depinning and subsequent motion of magnetic edge dislocations. The motion of these topologically stable objects triggers perturbations that can propagate over mesoscopic length scales. The observation of stochastic instabilities in the micromagnetic structure provides insight to the spatio-temporal dynamics of itinerant helimagnets and topological defects, and discloses open challenges regarding their technological usage.
Highlights
Chiral magnetic interactions induce complex spin textures including helical and conical spin spirals, as well as particle-like objects such as magnetic skyrmions and merons
Conventional microscopy methods, such as Lorentz transmission electron microscopy, magnetic force microscopy (MFM)[26] and scanning tunnelling microscopy[27], make either use of an electron beam or a magnetic probe tip and can themselves influence the behaviour of the spin structure
We study emergent micromagnetic dynamics in the helimagnetic phase of FeGe based on MFM, Nitrogen vacancy (NV) centre magnetometry, and Landau–Lifschitz–Gilbert (LLG) simulations
Summary
Chiral magnetic interactions induce complex spin textures including helical and conical spin spirals, as well as particle-like objects such as magnetic skyrmions and merons. These spin textures are the basis for innovative device paradigms and give rise to exotic topological phenomena, being of interest for both applied and fundamental sciences. The competition of ferromagnetic exchange, Dzyaloshinskii–Moriya (DM) interaction, and magnetic anisotropy leads to a variety of complex magnetic phases with spins forming helical or conical spirals, as well as long-range-ordered lattices of magnetic whirls[10] These spin structures are appealing as they give rise to anomalous transport properties[11,12], exotic vortex domain walls[13] and unusual dynamic spin-wave phenomena[14,15,16]. This technique has already been used successfully to study, for example, vortices[30], domain walls[31,32] and spin wave excitations[33,34] in ferromagnets, but it has never been used to probe (helical) antiferromagnetic spin arrangements and rarely been applied under cryogenic conditions[35,36]
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