- The paper demonstrates that additive interfacial DMI in Ir/Co/Pt multilayers stabilizes sub-100 nm skyrmions at room temperature.
- The study employs micromagnetic simulations and experiments to confirm a DMI strength of approximately 1.9 ± 0.2 mJ/m².
- This work paves the way for ultra-dense memory and logic devices by enabling robust, nanoscale magnetic skyrmions in practical conditions.
Additive Interfacial Chiral Interaction in Multilayers for Stabilization of Small Individual Skyrmions at Room Temperature
The paper provides a comprehensive investigation into the formation, stabilization, and potential applications of magnetic skyrmions in cobalt-based asymmetric multilayers. The authors focus on leveraging Dzyaloshinskii-Moriya Interaction (DMI) to stabilize sub-100 nm skyrmions at room temperature, an important step toward their utilization in next-generation data storage technology.
Magnetic skyrmions, characterized by a topologically protected whirlwind of spins, offer a promising route to overcome the storage density limitations of current hard disk technologies. Their robustness against defects and potential for manipulation using low electrical currents make them prime candidates for information storage and processing applications. Historically, skyrmions have been observed in bulk non-centrosymmetric materials below room temperatures. However, this paper successfully demonstrates the stabilization of skyrmions in technologically relevant multilayer films at room temperature.
Methodology
To achieve this, the authors designed multilayers where a cobalt (Co) layer is sandwiched between two heavy metals, iridium (Ir) and platinum (Pt). The intention was to produce additive DMI effects at the Co/Ir and Co/Pt interfaces. The multilayer system consists of ten repetitions of an {Ir(1 nm)|Co(0.6 nm)|Pt(1 nm)} trilayer. This stacking strategy is proposed to increase the DMI magnitude, thus stabilizing skyrmions across a range of layer thicknesses and external magnetic field conditions. Furthermore, the micromagnetic simulations conducted confirmed that these interactions allow skyrmion stabilization in the desired nanometer range.
Key Findings
The authors present a significant result: the confirmation of room temperature stabilization of isolated skyrmions in {Ir|Co|Pt} multilayers. The stability is primarily attributed to the strong additive interfacial DMI, measured at approximately 1.9 ± 0.2 mJ/m² for these materials, a key finding which suggests that multilayer architectures can achieve the desired DMI magnitude required for practical device integration. Experimental data matched closely with simulation predictions regarding skyrmion size as a function of the applied perpendicular magnetic field.
Another notable result is the observation of skyrmions in patterned nanodisks and nanostructures under room temperature conditions. This extension into nanoscale patterned systems is crucial for potential application in devices that rely on confined geometries. The micromagnetic simulations further assert the necessary threshold for DMI in achieving reduced skyrmion sizes within such constraints.
Implications and Future Directions
The findings provide a pathway for developing skyrmion-based memory and logic devices which can function efficiently at room temperature. This work lays the groundwork for further exploration of skyrmion manipulation through spin injections and the spin Hall effect, possibilities that could lead to reductions in device size and improvements in energy efficiency. One practical impact is the potential for ultra-dense memory storage solutions, given the small size and high stability of these skyrmions under ambient conditions.
On a theoretical level, this research underscores the interplay between interface engineering and spin-orbit interactions in modulating skyrmionic states. Future investigations could refine these multilayer structures to optimize for various parameters such as anisotropy, DMI, and exchange interactions, potentially reducing the skyrmion size further while maintaining their stability. Additionally, expanding this methodology to different material combinations might enable even more exotic spin textures and broaden the scope of applications.
As advancements in fabrication techniques continue, it stands to reason that practical, economical manufacturing of these multilayer structures could catalyze the adoption of skyrmion-based technologies across multiple domains, providing compelling solutions for the next era of data storage challenges. The paper, thus, represents a significant stepping stone in skyrmion research, balancing experimental achievement with theoretical insights.
