Magnon confinement and trapping at the nanoscale

Magnon confinement and trapping refer to the localization of magnons — quasiparticles that represent collective spin-wave excitations in magnetic materials — within specific regions or structures. This concept is essential in magnonics, a subfield of spintronics that leverages spin waves for processing and transmitting information. Compared to conventional electronics, magnonics offers lower power consumption and faster operation, making it a promising technology for future devices. Magnons can be confined using both static and dynamic methods, often relying on potential wells and barriers to restrict their free propagation and trap them in designated locations. In this review, we will explore the main strategies for magnon confinement and trapping, including: magnetic field inhomogeneities, spin textures (i.e. domain walls, vortices, skyrmions) nanostructured materials (i.e. nanowires, disks, and magnonic crystals), topological states, chiral magnons and flat band formation, induced by dipole–dipole interactions and Dzyaloshinskii–Moriya interaction. Microwave cavities and resonant magnetic fields, as well as spin-torque effects and Bose–Einstein condensation contribute to magnon localization. Furthermore, spin-wave edge and cavity modes have been observed in two-dimensional magnetic materials and twisted moiré superlattices at a specific twist angle. Magnon trapping has broad applications in computing and data processing, particularly in the development of magnonic crystals, waveguides, and memory elements. Additionally, magnon systems are being explored for quantum computing, where confinement can enhance the coupling between magnons and other quasiparticles in hybrid quantum systems. Precision control of magnons could lead to next-generation spintronic devices, offering improved efficiency and scalability.