Research

Three-dimensional and curvilinear nanomagnetism

Curvature and torsion modify the magnetic energy landscape through effective anisotropy and chiral interactions, and with it the ground state, the domain walls and the dynamics of a nanostructure. In curved and three-dimensional conduits, curvature and confinement also modify the spin-wave spectrum and introduce nonreciprocity.

We fabricate three-dimensional magnetic nanostructures by focused-electron-beam-induced deposition and grow curved thin films on pre-patterned substrates. Recent results include the curvature-controlled energy landscape of a Bloch point domain wall, the magnetization reversal of double-helix nanowires, and nonreciprocal spin waves in nanoscale domain walls.

Skyrmions and higher-order spin textures

Skyrmions and antiskyrmions of higher topological charge are stable at room temperature in multilayers with dominant dipolar interactions. We stabilize such textures, identify them by magnetic force microscopy, and investigate their dynamics, from the breathing mode and the spin-wave modes of the texture to topological collapse, by optical and microwave excitation and time-resolved X-ray microscopy.

Spin-orbit-torque-driven reconfiguration of the domain state in chiral multilayers further enables three-dimensional magnetic field sensing with a single Hall-bar device.

Hybrid magnon–phonon systems

The elastic eigenmodes of a three-dimensional nanostructure lie in the same frequency range as its spin-wave modes, and magnetoelastic coupling allows the two to exchange energy. We study this coupling in three-dimensional architectures, where the geometry determines both spectra. This is the newest research direction of the group.

Nanofabrication, lab-based high-frequency characterization and X-ray microscopy at large-scale facilities are combined with micromagnetic simulation, which guides the sample design and supports the interpretation of the measurements.

Fabrication

Thin-film deposition, electron-beam and photolithography, and three-dimensional nanostructuring with focused electron and ion beams

Transport

Magneto-transport on patterned devices

Dynamics

Ferromagnetic resonance and propagating spin-wave spectroscopy

Imaging

Time-resolved scanning transmission X-ray microscopy at synchrotron sources

Simulation

Finite-difference and finite-element micromagnetics and elastic eigenmode solvers; see Software