The Physics Colloquium is a series of lectures at the Institute of Physics. This week, Dr Kai Litzius presents his current research work:
Chiral magnetic textures, such as domain walls and skyrmions, are intriguing nanoscale structures with non-trivial topology, making them prime candidates for future spintronic devices. Their stability and controllability under various external stimuli – ranging from electric currents and magnetic fields to light and spin-orbit torques (SOTs) – open exciting avenues for next-generation memory and logic applications. In this talk, I will explore how these textures can be manipulated across different materials and excitation regimes, shedding light on fundamental physics and potential device applications.
I will first discuss the dynamics of skyrmions driven by electric currents, particularly in 2D van der Waals magnets such as Fe₃GeTe₂. Unlike conventional thin films, where disorder often disrupts skyrmion motion, these materials exhibit temperature-dependent creep-like motion with remarkably controlled trajectories. This behavior stems from the single-crystalline nature of exfoliated 2D layers, demonstrating how intrinsic material properties can be leveraged for efficient spintronic functionality – especially in the context of emerging room-temperature 2D magnets. Building on this, I will introduce recent findings on SOT-driven motion in engineered anisotropic racetracks, where we uncover transiently chaotic skyrmion dynamics using time-resolved x-ray holography and micromagnetic simulations. Surprisingly, despite the apparent chaos – marked by sub-nanosecond fluctuations, skyrmion shedding, and topological switching – these dynamics evolve into deterministic final states, suggesting new strategies for nanoscale magnetization control.
In the second part of the talk, I will turn to light-induced motion of spin textures in ferrimagnetic Pt/GdCo/Ta films. By employing focused laser pulses, we demonstrate arbitrary-direction displacement of domain walls and skyrmions, driven by an interplay of the Dzyaloshinskii-Moriya interaction (DMI), thermal gradients, and all-optical switching effects. Micromagnetic simulations provide further insight into how DMI stabilizes soliton dynamics, enabling reproducible, steerable motion in continuous films.
Together, these results offer a broad perspective on the dynamic behavior of chiral topological textures, highlighting opportunities for designing new and versatile spintronic devices.
