Upon optical excitation, the dynamics of different layers of magnetic alloys or heterostructures may show distinct dynamics, driven by processes such as OISTR (optical intersite spin transfer), spin currents, site-specific spin-orbit coupling, or magnon scattering strengths. We investigate these phenomena using broadband high harmonic spectroscopy, taking advantage of its ultrahigh temporal resolution and sensitivity to element-specific magnetisation.
 

1. Optical inter-site spin transfer probed by energy and spin-resolved transient absorption spectroscopy
   F. Willems, C. von Korff Schmising, C. Strüber, D. Schick, D. W. Engel, J. K. Dewhurst, P. Elliott, S. Sharma and S. Eisebitt
   Nature Communications 11, 871 (2020)
   DOI:10.1038/s41467-020-14691-5
2. Direct versus indirect excitation of ultrafast magnetization dynamics in FeNi alloys
   C. von Korff Schmising, S. Jana, O. Zülich, D. Sommer and S. Eisebitt
   Physical Review Research 6, 013270 (2024)
   DOI: 10.1103/PhysRevResearch.6.013270
3. Evidence of an exchange-based origin of demagnetization from the fluence dependent delay of Ni in a disordered Fe_0.5⁢Ni_0.5 alloy
   S. Jana, R. Knut, P. Singh, K. Yao, C. Tzschaschel, J. Richter, D. Schick, D. Sommer, D. Engel, O. Karis, C. von Korff Schmising and S. Eisebitt
   Physical Review B 112, 214412 (2025)
   DOI: 10.1103/f39s-kvy8 
4. Ultrafast behavior of induced and intrinsic magnetic moments in CoFeB/Pt bilayers probed by element-specific spectroscopy in the extreme ultraviolet spectral range
   C. von Korff Schmising, S. Jana, K. Yao, M. Hennecke, P. Scheid, S. Sharma, M. Viret, J.-Y. Chauleau, D. Schick, S. Eisebitt Phys. Rev. Res. 5, 013147 (2023)
   https://doi.org/10.1103/PhysRevResearch.5.013147

This research programme explores the use of ultrashort laser pulses for switching magnetisation, examining how this process can be scaled down to the nanometre scale.

1. All-Optical Switching on the Nanometer Scale Excited and Probed with Femtosecond Extreme Ultraviolet Pulses
   K. Yao, F. Steinbach, M. Borchert, D. Schick, D. Engel, F. Bencivenga, R. Mincigrucci, L. Foglia, E. Pedersoli, D. De Angelis, M. Pancaldi, B. Wehinger, F. Capotondi, C. Masciovecchio, S. Eisebitt and C. von Korff Schmising
   Nano Lett. 22, 4452 (2022)
   DOI: 10.1021/acs.nanolett.2c01060
2. Exploring the Fundamental Spatial Limits of Magnetic All-Optical Switching
   F. Steinbach, U. Atxitia, K. Yao, M. Borchert, D. Engel, F. Bencivenga, L. Foglia, R. Mincigrucci, E. Pedersoli, D. De Angelis, M. Pancaldi, D. Fainozzi, J. S. Pelli Cresi, E. Paltanin, F. Capotondi, C. Masciovecchio, S. Eisebitt and Clemens von Korff Schmising 
   Nano Letters 24, 6865 (2024)
   DOI: 10.1021/acs.nanolett.4c00129
3. Subwavelength Localized All-Optical Helicity-Independent Magnetic Switching Using Plasmonic Gold Nanostructures
   T.P.H. Sidiropoulos,P. Singh, T. Noll, M. Schneider, D. Engel, D. Sommer, F. Steinbach, I. Will, B. Pfau, C. von Korff Schmising, Stefan Eisebitt
   Nano Letters 25 4645 (2025)
   https://doi.org/10.1021/acs.nanolett.4c04024

When optically excited, thin magnetic heterostructures can develop a transient magnetic depth profile on a length scale of only a few nanometres. This phenomenon may be driven by ultrafast spin and electron currents, temperature profiles, or interface effects. We have developed a new experimental technique based on broadband soft X-ray reflectometry that can directly resolve such spatiotemporal evolutions of laser-induced spin dynamics.

1. Ultrafast element- and depth-resolved magnetization dynamics probed by transverse magneto-optical Kerr effect spectroscopy in the soft x-ray range
   M. Hennecke , D. Schick , T. Sidiropoulos, F. Willems, A. Heilmann, M. Bock, L. Ehrentraut, D. Engel, P. Hessing, B. Pfau, M. Schmidbauer, A. Furchner, M. Schnuerer, C. von Korff Schmising and S. Eisebitt  
   Phys. Rev. Research 4, L022062 (2022)
   DOI: 10.1103/PhysRevResearch.4.L022062
2. Transient domain boundary drives ultrafast magnetisation reversal
   M. Hennecke, D. Schick, T. P. H. Sidiropoulos, J.-X. Lin, Z. Guo, G. Malinowski, M. Mattern, L. Ehrentraut, M. Schmidbauer, M. Schnuerer, C. von Korff Schmising, S. Mangin, M. Hehn and S. Eisebitt
   Nature Communications 16, 8233 (2025)
   DOI:10.1038/s41467-025-63571-3