Periodic Reporting for period 1 - SPEEDY (SPin tExturEs and DYnamics in 3D complex nanostructures)
Reporting period: 2023-04-01 to 2025-03-31
In a world driven by technological advances, the "SPEEDY" project aims to deepen the understanding of three-dimensional nanomagnetic systems. These systems, with novel and unconventional spin textures, are an exciting platform to explore new magnetic phenomena making them promising systems for the development of more efficient, capable and multifunctional technologies.
The objective of SPEEDY is to pioneer an experimental understanding of magnetic domain wall dynamics within complex three-dimensional structures. Magnetic domain walls, which are soliton-like textures, form the basis of many proposed spintronics devices in recent years. However, despite their potential, many of these exciting properties remain theoretical and have yet to be realized experimentally. Led by S. Ruiz-Gomez at the Max Planck Institute for Chemical Physics of Solids, SPEEDY seeks to investigate the influence of three-dimensional geometry, including curvature and torsion, on domain wall motion. Through meticulously designed systems of increasing complexity, the project endeavours to unravel the intricate dynamics governing these magnetic structures.
The proposed research addresses challenges for sustainable technologies from a two-fold perspective. Firstly, It delves into the fundamental research on 3D magnetic nanosystems where the understanding of the physics of the domain wall motion in 3D conduits can lead to technological applications such as new logic and/or information storage devices.
Secondly, the project aims to harness the acquired knowledge to design devices with significant potential impact in the field of Information and Communication Technologies (ICT). The combination of these two approaches makes SPEEDY an excellent platform to contribute towards the goals of the Innovation Union and has a strong potential to impact research and innovation in the European Union.
The objective of SPEEDY is to pioneer an experimental understanding of magnetic domain wall dynamics within complex three-dimensional structures. Magnetic domain walls, which are soliton-like textures, form the basis of many proposed spintronics devices in recent years. However, despite their potential, many of these exciting properties remain theoretical and have yet to be realized experimentally. Led by S. Ruiz-Gomez at the Max Planck Institute for Chemical Physics of Solids, SPEEDY seeks to investigate the influence of three-dimensional geometry, including curvature and torsion, on domain wall motion. Through meticulously designed systems of increasing complexity, the project endeavours to unravel the intricate dynamics governing these magnetic structures.
The proposed research addresses challenges for sustainable technologies from a two-fold perspective. Firstly, It delves into the fundamental research on 3D magnetic nanosystems where the understanding of the physics of the domain wall motion in 3D conduits can lead to technological applications such as new logic and/or information storage devices.
Secondly, the project aims to harness the acquired knowledge to design devices with significant potential impact in the field of Information and Communication Technologies (ICT). The combination of these two approaches makes SPEEDY an excellent platform to contribute towards the goals of the Innovation Union and has a strong potential to impact research and innovation in the European Union.
The main goal of this project is to control the DW dynamics in three-dimensional systems through the effects of the 3D geometry, including curvature, topology, and chirality. To achieve this aim our initial focus was to elucidate the influence of these three-dimensional effects on the domain wall dynamics through systematic investigations of carefully designed 3D systems.
The project has addressed the following goals:
1. Stabilization of spin textures in curved nanostructures: Two types of domain walls are commonly observed in cylindrical nanowires: transverse vortex domain walls (TDWs) and Bloch point domain walls (BPDWs). TDWs involve a rotation of magnetisation perpendicular to the wire axis, while BPDWs feature a curvature of magnetic moments within a plane perpendicular to the wire axis, with a Bloch point at its centre. While the effect of curvature-induced symmetry breaking has been explored for TDWs, allowing the selection of the chirality of TDWs, the stabilisation of BPDWs presents a new opportunity to investigate their fundamental properties. Bloch point singularities, known for their topological nature, are of interest for both fundamental research and technological applications, as they represent one of the smallest magnetic textures suitable for information storage, with is expected to show ultrafast velocities. However, our understanding of these singularities and our ability to control them experimentally have been limited. In this project we succeeded in stabilising BPDW by introducing curvature into the system. By fabricating a model nanowire system with curvature-induced variable DMI regions separated by straight chiral segments, we demonstrate the stabilisation of the domain walls within the straight regions using high X-ray magnetic microscopy.
2. Pinning in undulating conduits: Through experimental observations, we have identified that BPDWs tend to pin in straight sections of nanostructures between curved regions. Micromagnetic finite element simulations shed light on the influence of curvature-induced symmetry breaking on the energy of BPDWs. The achiral nature of BPDWs makes them susceptible to being pin in straight and achiral regions, which are stable energy minima for this kind of domain walls.
3. Propagation of Bloch point domain walls in undulating conduits: Exploiting the energy dependence of BPDWs, we introduce regions of varying curvature to control the energy landscape, creating well-defined pinning points. By patterning the curvature, we engineer asymmetric potential wells that induce non-reciprocal motion of BPDWs. This control of the energy landscape enables the realization of a robust Bloch point shift-register with tuneable depinning fields and non-reciprocal behaviour.
4. Integrated DW conduits: To translate these fundamental discoveries into practical applications, we need to integrate nanostructures into devices. By directly depositing FEBID Co nanostructures on chips, we enable the application of electric currents to control the magnetic state and the domain wall motion. These integrated nanostructures demonstrate suitable conductivity for electrical measurements, paving the way for the development of spintronic devices based on current control.
The project has addressed the following goals:
1. Stabilization of spin textures in curved nanostructures: Two types of domain walls are commonly observed in cylindrical nanowires: transverse vortex domain walls (TDWs) and Bloch point domain walls (BPDWs). TDWs involve a rotation of magnetisation perpendicular to the wire axis, while BPDWs feature a curvature of magnetic moments within a plane perpendicular to the wire axis, with a Bloch point at its centre. While the effect of curvature-induced symmetry breaking has been explored for TDWs, allowing the selection of the chirality of TDWs, the stabilisation of BPDWs presents a new opportunity to investigate their fundamental properties. Bloch point singularities, known for their topological nature, are of interest for both fundamental research and technological applications, as they represent one of the smallest magnetic textures suitable for information storage, with is expected to show ultrafast velocities. However, our understanding of these singularities and our ability to control them experimentally have been limited. In this project we succeeded in stabilising BPDW by introducing curvature into the system. By fabricating a model nanowire system with curvature-induced variable DMI regions separated by straight chiral segments, we demonstrate the stabilisation of the domain walls within the straight regions using high X-ray magnetic microscopy.
2. Pinning in undulating conduits: Through experimental observations, we have identified that BPDWs tend to pin in straight sections of nanostructures between curved regions. Micromagnetic finite element simulations shed light on the influence of curvature-induced symmetry breaking on the energy of BPDWs. The achiral nature of BPDWs makes them susceptible to being pin in straight and achiral regions, which are stable energy minima for this kind of domain walls.
3. Propagation of Bloch point domain walls in undulating conduits: Exploiting the energy dependence of BPDWs, we introduce regions of varying curvature to control the energy landscape, creating well-defined pinning points. By patterning the curvature, we engineer asymmetric potential wells that induce non-reciprocal motion of BPDWs. This control of the energy landscape enables the realization of a robust Bloch point shift-register with tuneable depinning fields and non-reciprocal behaviour.
4. Integrated DW conduits: To translate these fundamental discoveries into practical applications, we need to integrate nanostructures into devices. By directly depositing FEBID Co nanostructures on chips, we enable the application of electric currents to control the magnetic state and the domain wall motion. These integrated nanostructures demonstrate suitable conductivity for electrical measurements, paving the way for the development of spintronic devices based on current control.
The project had the goal of manipulating domain wall (DW) dynamics within three-dimensional (3D) systems, harnessing the intricate interplay of 3D geometry, including curvature, topology, and chirality. By using advanced 3D nanopatterning we can carefully design nanostructures where we control the local symmetry breaking and effective DMI by defining curved regions along them. In this way, we first demonstrate the stabilization of Bloch point Domain Walls that walls predominantly exist in straight, achiral regions of the sample. The experimental observations and micromagnetic simulations shed light on the pinning mechanisms of BPDWs in this section. This understanding of curvature-induced symmetry breaking and its influence on the energy landscape of BPDWs is crucial for further exploration and control of domain wall behavior in 3D systems. By propagating this kind of domain walls through nanostructure with varying curvature we demonstrate the realization of a robust Bloch point shift-register with tunable depinning fields and non-reciprocal behavior.
the project's results represent significant advancements in the field of magnetism and spintronics, offering new insights into the manipulation and control of domain wall dynamics in three-dimensional systems. These findings not only deepen our understanding of fundamental phenomena but also lay the groundwork for the development of innovative technologies with potential applications in information storage, processing, and communication. Moving forward, further research and demonstration efforts will be needed to evaluate the scalability and reliability of the proposed methods for controlling domain wall dynamics in 3D systems what can open the way for the realization of practical devices.
the project's results represent significant advancements in the field of magnetism and spintronics, offering new insights into the manipulation and control of domain wall dynamics in three-dimensional systems. These findings not only deepen our understanding of fundamental phenomena but also lay the groundwork for the development of innovative technologies with potential applications in information storage, processing, and communication. Moving forward, further research and demonstration efforts will be needed to evaluate the scalability and reliability of the proposed methods for controlling domain wall dynamics in 3D systems what can open the way for the realization of practical devices.