Non-collinear magnetism and zero-field skyrmions in all-light-metal multilayers*

Magnetic skyrmions [1] are at the core of many recently proposed spintronic devices. Most of the thin film multilayers hosting magnetic skyrmions [2-3] are characterized by [heavy metals]\ferromagnet interfaces to generate a strong Dzyaloshinskii-Moriya interaction (DMI) and usually an external magnetic field is needed to stabilize the skyrmions. From an application point of view, both the use of heavy metals (rare and expensive) and the need for an external magnetic field (incompatible with nanoelectronics due to scalability issues) are limitations. Accordingly, it is highly desirable to have [light metal]-based systems capable of hosting skyrmions at zero field.
Here, I will first discuss the observation of magnetic domain walls with uni-directional sense of rotation in [light-metal]\ferromagnet multilayers. Density functional theory calculations allows us to understand the origin and predict the strength of the DMI in those systems, which compares well with experimental values. Subsequently, I will discuss how such systems can be employed for the stabilization of isolated magnetic skyrmions at room temperature and zero magnetic field via interlayer exchange coupling (IEC) [4,5]. By carefully adjusting the IEC in the system we can tune the size of the observed skyrmions. Those findings open up the possibility to develop cost-effective skyrmion-based spintronic devices suitable for general-user applications which go beyond modern nanoelectronics.

[1] N. Romming et al., Science 341, 636 (2013).
[2] C. Moreau-Luchaire et al., Nat. Nanotechnol. 11, 444 (2016).
[3] A. Soumyanarayanan et al., Nat. Mater. 16, 898 (2017).
[4] G. Chen et al., Appl. Phys. Lett. 106, 242404 (2015).
[5] R. Lo Conte et al., Nano Lett. 20, 4739 (2020).