An Artificial Skyrmion Platform with Robust Tunability in Synthetic Antiferromagnetic Multilayers

Abstract

Magnetic skyrmions are topologically non-trivial spin structure, and their existence in ferromagnetically coupled multilayers has been reported with disordered arrangement. In these multilayers, the heavy metal spacing layers provide an interfacial Dzyaloshinskii-Moriya interaction (DMI) for stabilizing skyrmions at the expense of interlayer exchanging coupling (IEC). To meet the functional requirement of ordered/designable arrangement, in this work, we proposed and experimentally demonstrated a scenario of skyrmion nucleation using nanostructured synthetic antiferromagnetic (SAF) multilayers. Instead of relying on DMI, the antiferromagnetic IEC in the SAF multilayers fulfills the role of nucleation and stabilization of skyrmions. The IEC induced skyrmions were identified directly imaged with MFM and confirmed by magnetometry and magnetoresistance measurements as well as micromagnetic simulation. Furthermore, the robustness of the proposed skyrmion nucleation scenario was examined against temperature (from 4.5 to 300 K), device size (from 400 to 1200 nm), and different lattice designs. Hence, our results provide a synthetic skyrmion platform meeting the functional needs in magnonic and spintronic applications.

Hybrid quantum systems based on magnonics

“…Beside the theoretical and numerical studies on SMCs, we will also review experimental achievements on the dynamic modes of skyrmion crystals, and building artificial skyrmion crystals, both of which can promote the application of SMCs for future magnonic devices. [100][101][102][103][161][162][163][164][165][166] .…”

“…8(a) and 8(b). In 2020, Y. Li et al provided a new method to build artificial skyrmion lattice in top-layernanostructured synthetic antiferromagnetic (SAF) multilayers via the interlayer antiferromagnetic coupling 165 , which is illustrated in Fig. 8(c).…”

Material systems for FM-/AFM-coupled skyrmions in Co/Pt-based multilayers

“…Synthetic antiferromagnetic (SAF) multilayers [31][32][33][34], i.e., ferromagnetic (FM) films separated by an ultrathin antiferromagnetic coupling interlayer, offer a promising platform to resolve these issues associated with skyrmions in ferromagnetic MMLs. Recently, antiferromagnetically (AFM) coupled magnetic bilayer-skyrmions (see Fig.…”

“…Although compared to ferromagnetic skyrmions [45][46][47][48][49] some advantages have theoretically been predicted for AFM-coupled skyrmions, such as higher speed, smaller size and more stability, and it has been shown experimentally that skyrmions in SAF have the potential to be small and stable, material systems that could host AFM-coupled skyrmions with optimal properties are still rare. At present, Ruthenium is typically used to experimentally induce AFM coupling in Cobased multilayers [34,44,[50][51][52]. Therefore, the search for SAF materials that can accommodate AFM-coupled skyrmions is an important task in skyrmion research.…”

Magnetotransport studies of heterostructures based on transition metals and their oxides

“…Embedding antiferromagnetic interlayer exchange coupling through a nonmagnetic spacer [150] is a promising solution. These artificial antiferromagnets, which are referred to as synthetic antiferromagnets (SAFs) [147,[151][152][153], introduce special spin textures, such as antiferromagnetic skyrmion [154] and antiferromagnetically-coupled bilayer skyrmion [147,153]. Therefore, a combination of SAFs and skyrmion crystals might permit new functionalities and boost the control of skyrmions.…”