TRR 227:  Ultrafast Spin Dynamics

• Subject Area: Physics
• Term: since 2018
• Website: Homepage
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 328545488

The electron spin is one of the key quantum properties determining structure and dynamics of matter. It has large potential for applications in future magnetic memory and logic devices with simple architecture and reduced power consumption. Two fundamental spin-dependent interactions, exchange and spin-orbit coupling, allow for a spin response down to ultrafast time scales. Likewise, when reaching the nanoscale, electron and spin transport become ballistic and can occur ultrafast within femtoseconds. However, while such high speed and terahertz (THz) bandwidths are required for future applications, most present-day spintronic devices operate at 100-1000 times lower clock rates. The goal of our CRC/TRR is to establish a fundamental understanding of ultrafast spin dynamics, thereby laying the foundations for spin-based information technology that can be operated at THz clock rates. Our concerted research effort comprises cutting-edge experiments in ultrafast spectroscopy and multiscale theoretical modeling of spin dynamics. To study ultrafast spin dynamics, we make use of the fastest stimuli and probes available: ultrashort optical and electromagnetic pulses with center frequencies ranging from the THz to the ultraviolet spectral range. In the 1st funding period, this science-driven approach has led to a wealth of new results, fundamental knowledge, and novel functionalities. They are documented in 150 publications, 50 of which are co-authored by two or more project leaders. For the new funding period, we are prepared to extend our material basis by a set of novel and prototypical materials with more complex spin structure, for example natural and synthetic antiferromagnets and two-dimensional magnets. We will tune spin couplings in layered systems and, in a number of cases, use nanoscale plasmonic structures to localize and enhance incident and emitted electromagnetic fields. These approaches will allow us to explore novel ways of efficient manipulation, control and interrogation of spin systems at THz rates and on nanometer length scales. The long-term goal is to transfer the understanding of femtosecond spin dynamics into novel functionalities for future ultrafast spin-based technology. Our research consortium employs and develops a comprehensive portfolio of experimental and theoretical methods that is ideally suited to study ultrafast spin dynamics and train our graduate students in this scientifically exciting and technologically promising field of condensed-matter physics.

• DFG Programme: CRC/Transregios

Current projects

• A01 - Ultrafast spin dynamics and its signature in the transient electronic structure (Project Head Weinelt, Martin )
• A02 - Ultrafast spin dynamics in heterogeneous magnetic systems (Project Heads Eisebitt, Stefan ;  von Korff Schmising, Clemens )
• A03 - Element specific view on ultrafast spin and orbital angular momentum redistribution (Project Heads Föhlisch, Alexander ;  Pontius, Niko ;  Schüßler-Langeheine, Christian )
• A04 - Ultrafast spin dynamics combined with nuclear dynamics in 2D and 3D (Project Heads Dewhurst, John Kay ;  Sharma, Ph.D., Sangeeta )
• A05 - Elementary terahertz spin interactions in magnetic solids (Project Heads Dörr, Kathrin ;  Kampfrath, Tobias ;  Seifert, Tom Sebastian )
• A06 - Nanometer-resolved ultrafast spin and electron dynamics at magnetic surfaces (Project Heads Chiang, Cheng-Tien ;  Widdra, Wolf )
• A07 - Bridging the time scales between ultrafast and precessional magnetization dynamics (Project Head Kuch, Wolfgang )
• A10 - Spin-lattice coupling on ultrafast time scales (Project Heads Bargheer, Matias ;  Ernstorfer, Ralph ;  Windsor, Yoav William )
• B01 - Ultrafast spin currents and spin torques studied by (non-) linear magneto-optics (Project Heads Melnikov, Alexey ;  Woltersdorf, Georg )
• B02 - Ultrafast spintronic devices (Project Heads Kampfrath, Tobias ;  Schmidt, Georg ;  Woltersdorf, Georg )
• B03 - Time-dependent spin dynamics and electron transport (Project Head Brouwer, Piet W. )
• B04 - Spin-dependent transport in inhomogeneous systems (Project Heads Henk, Jürgen ;  Mertig, Ingrid )
• B05 - Spin dynamics in atomically-precise nanostructures (Project Heads Franke, Katharina ;  Kampfrath, Tobias )
• B06 - Imaging and control of spatio-temporal spin dynamics in nanostructures (Project Head Berakdar, Jamal )
• B07 - Momentum-resolved dynamics of relaxation processes and control of spins and pseudospins in two-dimensional spintronic heterostructures (Project Heads Ernstorfer, Ralph ;  Gahl, Cornelius ;  Rettig, Laurenz ;  Wolf, Martin )
• B08 - Controlling ultrafast spin dynamics in two-dimensional materials via mechanical strain and proximal excitations (Project Heads Bolotin, Kirill ;  Gahl, Cornelius )
• B10 - Ultrafast control of Berry-curvature-driven transport via spin-torque excitation of chiral magnets (Project Heads Parkin, Stuart ;  Taylor, James M. ;  Woltersdorf, Georg )
• B11 - Probing exciton structure and dynamics in two-dimensional magnets and spintronic heterostructures (Project Head Seiler, Hélène )
• MGK - Integrated Research Training Group (Project Heads Franke, Katharina ;  Widdra, Wolf )
• Z - Central Tasks of the Collaborative Research Center / Transregio (Project Head Weinelt, Martin )

Completed projects

• A08 - Multiscale modeling of ultrafast spin dynamics (Project Head Atxitia Macizo, Ph.D., Unai )
• A09 - Ultrafast magnetization dynamics and spin transport in magnetic oxide heterostructures (Project Head Rettig, Laurenz )
• B09 - Real-time (pseudo-)spin transport and dynamics in transition metal dichalcogenides (Project Head Marques, Miguel )

• Applicant Institution: Freie Universität Berlin
• Co-Applicant Institution: Martin-Luther-Universität Halle-Wittenberg
• Participating Institution: Fritz-Haber-Institut der Max-Planck-Gesellschaft (FHI); Helmholtz-Zentrum Berlin für Materialien und Energie; Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie; im Forschungsverbund Berlin e.V.; Max-Planck-Institut für Mikrostrukturphysik
• Participating University: Technische Universität Berlin; Universität Potsdam
• Spokesperson: Professor Dr. Martin Weinelt