The Laboratory of Nanoscale Magnetic Materials and Magnonics (LMGN) at EPFL explores magnetic and superconducting nanomaterials for applications in information technology (data processing, transmission, logic), sensing and multifunctional devices.  We prepare and investigate individual ferromagnetic nanostructures such as nanotubes, periodic and aperiodic nanomagnet arrangements such as two- and three-dimensional magnonic crystals, artificial spin ice and quasicrystals as well as skyrmion lattices. From superconductors such as TiN and NbN we prepare free-form 3D quantum devices. We study their fundamental properties and search for novel functionalities.
By our experiments and simulations, we aim at obtaining a microscopic understanding about how to master collective spin excitations and spin-polarized (supre)currents at the nanoscale. The focus is devoted to microwave properties covering the frequency regime from about 1 GHz to 1 THz. In this regime, electromagnetic waves that, in free space, exhibit wavelengths from mm to cm can be coupled to the microscopic magnetic moments, thereby inducing spin-precessional motion (spin waves). The wave-like excitation can obey a wavelength of a few 10 nanometers and smaller. Miniaturized microwave components are hence possible. By our projects we contribute to the research fields magnonics and super-spintronics where one aims at data processing and transmission using spin waves and spin-polarized supercurrents in nanoengineered magnetic circuits. The main challenges in the research field are as follows:

LMGN follows research along these different lines in national and international collaborations.

Superconducting materials are important in quantum science and engineering as well as in applications where high magnetic fields are required (such as magnetic resonance imaging). We investigate the physical properties of 3D superconducting nanostructures which are subject to an applied magnetic field and whose surfaces exhibit engineered curvatures with unprecedentedly small radii. We expect to induce novel superconducting characteristics which might be relevant for next-generation sensors and quantum computing architectures. By using numerical methods, we first study the interplay of geometry and transport currents with and without topological defects such as Abrikosov vortices on curved surfaces (see illustration). In future research we will then fabricate and measure superconducting spherical shells, nanotubular structures and 3D lattices of interconnected nanotubes which can function as vias in 3D superconducting circuits.

Magnonic Crystals, Grating Couplers & Hardware-implemented Neural Networks

Periodically and aperiodically arranged nanomagnets are explored concerning quasistatic and dynamic properties in planar magnonic circuits. They can be used to tailor band structures for spin waves and thereby manipulate microwave signals on the nanoscale. We have shown that a ferromagnetic nanodisk array on a magnetic thin film serves as an efficient microwave-to-magnon transducer – a key device for magnonics and neural networks.

Nanotubes & Artificial Chiral Magnets

We prepare and explore chiral ferromagnetic nanotubes and 3D which can host topologically protected solitons (domain walls) and geometrically confined magnon modes. The nanotubes are formed as shells on filamentary semiconductor crystals, i.e., semiconductor nanowires, and on polymeric nanotemplates created by two-photon lithography.