Linear optics

In our group we apply various linear optical methods. This starts from using basic characterization tools like linear transmission or reflection spectroscopy to investigate the electronic states of matter to sophisticated methods deploying the magneto-optical Faraday or Kerr effect to trace the ultrafast dynamics of complex magnetic ordering or the imaging of magnetic domains.

Spatial resolution can deepen our knowledge about the material we are investigating. For the study of ferromagnetic domains we can take advantage of the Faraday or Kerr effect, which deal with the rotation of the polarization plane of light in a magnetized medium.

Faraday images of ferromagnetic domains in (a) 001-cut and (b) 011-cut DyTbFeO3 — Faraday images of ferromagnetic domains in (a) 001-cut and (b) 011-cut DyTbFeO₃

For the investigation of ferroic states in artificial materials consisting of two-dimensional periodic arrays of sub-micrometer ferromagnetic elements, we apply diffraction techniques. The analysis of magneto-optical signals in diffraction spots allows to access different light wave vectors, and thus, reveals nonreciprocal directional phenomena.

Left: Schematic of the diffraction process for sensing a nonreciprocal interaction associated with the crystal's y-axis. Right: diffraction pattern from a typical nanomagnetic array with hexagonal lattice symmetry. Highlighted are +ky and -ky spots. — Left: Schematic of the diffraction process for sensing a nonreciprocal interaction associated with the crystal's y-axis. Right: diffraction pattern from a typical nanomagnetic array with hexagonal lattice symmetry. Highlighted are +k_y and -k_y spots.