Realization of Isolated and High-Density Skyrmions at Room Temperature in Uncompensated Synthetic Antiferromagnets

Abstract

Magnetic skyrmions are vortex-like spin textures with nontrivial spin topology and novel physical properties that show promise as an essential building block for novel spintronic applications. Skyrmions in synthetic antiferromagnets (SAF) have been proposed long-term to have many advantages than those in ferromagnetic materials, which suffer from fundamental limits for size and efficient manipulation. Thus, experimental realization of skyrmions in SAF is intensely pursued. Here we show the observation of zero-field stable magnetic skyrmions at room temperature in SAF [Co/Pd]/Ru/[Co/Pd] multilayers with Lorentz transmission electron microscope, where uncompensated moments of the SAF provide a medium for the skyrmion characterization. Isolated skyrmions and high-density skyrmions via magnetic field and electromagnetic coordinated methods have been observed, respectively. These created high-density skyrmions maintain at zero-field even when both the current and magnetic field are removed. The use of skyrmions in SAF would advance the process toward practical nonvolatile memories based on spin topology.

Reducing Dzyaloshinskii-Moriya interaction and field-free spin-orbit torque switching in synthetic antiferromagnets

“…This can be understood from that the anomalous Hall coefficients of BM and TM layer are different, which can be ascribed to the sample growth condition. The anomalous Hall coefficient of [Co/Pd] multilayers grown on Ru is usually smaller than that deposited on Pt because of the smaller spin-orbit coupling of Ru 28,42,43 .…”

Operando control of skyrmion density in a Lorentz transmission electron microscope with current pulses

“…27 Almost contemporary to this work, current pulses have been applied to achieve high density skyrmions in a synthetic antiferromagnet heterostructure in the LTEM environment. 28 These works demonstrate the critical importance of integrating electrical current driven skyrmion devices with biasing holders that enable operando LTEM measurements.…”

Perpendicularly magnetized Co/Pd-based magneto-resistive heterostructures on flexible substrates

“…a topologically-protected solitons). [43][44][45] Albeit the high potential of PMA spintronic devices, no studies are reported, to the best of our knowledge, on exible magnetoresistive heterostructures with perpendicular magnetic anisotropy. Indeed, the stringent constrains needed to obtain highquality PMA magneto-resistive thin lm multi-stacks, requiring for a ne control of the stack properties at the subnanometer level, hinder the direct deposition on the most common exible polymeric tapes, which are amorphous and generally present a rougher surface and lower melting temperatures with respect to commonly used single-crystal rigid substrates (e.g.…”