Matias Bargheer

Prof. Dr. Matias Bargheer is a Professor of Physics at the University of Potsdam, where he leads the "Ultrafast Dynamics in Condensed Matter" research group within the Institute of Physics and Astronomy. He serves as a Principal Investigator in the Transregio Collaborative Research Center TRR 227 "Ultrafast Spin Dynamics" and is the spokesperson for the newly established Collaborative Research Center SFB 1636 "Elementary Processes of Light-Driven Reactions at Nanoscale Metals." His research focuses on understanding non-equilibrium phenomena in condensed matter systems on ultrafast timescales.

His research interests span several interconnected areas:

• Ultrafast magnetism and spin dynamics
• Plasmonics and light-matter interactions at the nanoscale
• Nanoscale heat transport and thermalization processes
• Ultrafast lattice dynamics and strain wave propagation
• Ferroelectric switching phenomena
• Development of advanced ultrafast experimental techniques

Bargheer's group investigates coherent and incoherent non-equilibrium phenomena at the nanoscale initiated by various external stimuli, particularly light and electromagnetic pulses. While incoherent processes transport heat and charges and may drive phase transitions and chemical reactions, coherent dynamics range from strain- and spin waves to strong coupling in exciton-plasmon systems. His specialty is combining ultrafast x-ray diffraction (UXRD) and transient magneto-optical Kerr effect (MOKE) experiments to selectively probe spin and lattice systems.

His recent publications reveal several key trends in his research. Bargheer's group has been investigating laser-induced phase transitions in materials like FeRh, demonstrating how plasmonic absorption can accelerate these transitions in nanostructured materials compared to continuous films. They have also made significant advances in controlling magnetization precession through nanoscale heterostructure design and double-pulse laser excitation techniques. Another major focus has been on understanding spin-phonon interactions and their role in generating coherent THz magnons in antiferromagnetic materials.

Among his notable achievements:

• Development of techniques to shape picosecond strain pulses using magnetostrictive transducers
• Demonstration of polarization-dependent control of ultrafast demagnetization in iron garnets
• Insights into finite-size effects in ultrafast remagnetization dynamics
• Discovery of unconventional picosecond strain pulses resulting from magnetic stress saturation
• Elucidation of spin stress contributions to lattice dynamics in magnetic materials

Bargheer has supervised numerous doctoral and master's students whose research has contributed significantly to the field of ultrafast condensed matter physics. His laboratory maintains advanced experimental capabilities including ultrafast x-ray diffraction at their own PXS source and at synchrotron BESSY II, time-resolved magneto-optical Kerr effect (tr-MOKE), time-domain Brillouin scattering, and specialized techniques for studying ferroelectric switching. The group also develops simulation tools like udkm1Dsim for modeling ultrafast dynamics in 1D nanostructures.