Laser writing for 3D control of magnetism at the nanoscale

An international research team led by Politecnico di Milano has developed an innovative technique to control magnetism in three dimensions at the nanometre scale within crystalline thin films of yttrium iron garnet (YIG). YIG is a key material for magnonics—an emerging field that exploits spin waves for both signal processing and the implementation of low‑power computing devices.

The proposed method is simple and single‑step: it uses a focused UV laser to permanently “write” complex magnetic patterns inside YIG films. In the study published in Nature Communications, the researchers show that UV irradiation produces a stable, localized increase in perpendicular magnetic anisotropy, a crucial material property. The resulting magnetic modification is confined both laterally and in depth, down to features of about 100 nanometres, without compromising the crystalline structure of YIG.

A further advantage of the technique is that the depth of the modification can be precisely tuned by adjusting the laser power, enabling continuous, truly three‑dimensional control of the magnetic profile.

This approach paves the way for the fabrication of complex magnetic architectures and “grayscale” metamaterials in thin YIG films, with potential applications in magnonic, magneto‑optical, and hybrid quantum devices.

The research was carried out by the PhyND group at the Department of Physics, Politecnico di Milano, in collaboration with the Department of Mechanics and the Department of Energy, Politecnico di Milano, the 10University of Perugia, RPTU University Kaiserslautern‑Landau, IFN‑CNR and CNR‑IOM, with support from the European Union (Horizon 2020 – B3YOND project), the Italian Ministry of University and Research, Fondazione Cariplo, and Fondazione CDP.