Deterministic Field-Free Skyrmion Nucleation at a Nanoengineered Injector Device

Abstract

Magnetic skyrmions are topological solitons that exhibit an increased stability against annihilation [1,2], and can be displaced with low current densities [3], making them a promising candidate as an information carrier [1]. In order to demonstrate a viable skyrmion-based memory device, it is necessary to reliably and reproducibly nucleate, displace, detect, and delete the magnetic skyrmions. While the skyrmion displacement [4-7] and detection [8,9] have both been investigated in detail, much less attention has been dedicated to the study of the sub-ns dynamics of the skyrmion nucleation process. Only limited studies on the statics [10, 11] and above-ns dynamics [12] have been performed, leaving still many open questions on the dynamics of the nucleation process. Furthermore, the vast majority of the presently existing studies focus on the nucleation from random natural pinning sites [10,12], or from patterned constrictions in the magnetic material itself [10,11], which limit the functionality of the skyrmion-based device. Those limitations can be overcome by the fabrication of a dedicated injector device on top of the magnetic material [13]. In this study, we investigate the nucleation of magnetic skyrmions from a dedicated nano-engineered injector, demonstrating the reliable magnetic skyrmion nucleation at the remnant state. The sub-ns dynamics of the skyrmion nucleation process were also investigated, allowing us to shine light on the physical processes driving the nucleation.

Skyrmion-based artificial synapses for neuromorphic computing

“…2b inset. The applied unipolar pulses during both potentiation and depression were designed and optimized to generate/delete the controlled number of skyrmions using current-induced spin-orbit torques (SOTs) as investigated in our previous study 11 , assisted by current-induced joule heating that contributes to the reduction of skyrmion switching thresholds 28 . In Fig.…”

Controlled Individual Skyrmion Nucleation at Artificial Defects Formed by Ion Irradiation

“…One crucial step necessary for realizing a skyrmion‐based device lies in finding a reliable and controllable method of nucleating individual skyrmions. A multitude of nucleation methods have been proposed in recent years and these can be put into three categories based on: electrical currents, [ 10,19–24 ] laser pulses, [ 25–27 ] and locally applied electric fields. [ 28,29 ] Skyrmions can also nucleate at naturally occurring defects in the material; [ 30,31 ] theoretical studies, which consider nonmagnetic defects, find that defects both localize skyrmion nucleation and reduce the nucleation energy barrier.…”

Additive Nano-Lithography with Focused Soft X-rays: Basics, Challenges, and Opportunities

“…Since synchrotron-based X-ray microscopes offer continuously tunable excitation photon energy, it has been shown that within a multilayer of several photoresists consecutively stacked at the same spot, each layer can be addressed separately by the resonant photon energy of the respective Following the development of suitable focusing optics for soft X-rays [49][50][51], the first soft X-ray microscopes were installed in the mid-1980s [52,53]. Since then, STXM has developed into a versatile method for characterization of suitably thin specimens from various scientific disciplines, such as biology, medicine, catalysis, material science, magnetism, geology, cosmology, and cultural heritage [54][55][56][57][58][59][60][61][62][63][64]. Figure 1 depicts a scheme of a modern STXM with all basic elements and their respective degrees of freedom [59,65,66].…”