Spin: Interaction and Control

Dr. Helmut Schultheiß

• Research Topics
• Methods
• Theses

Within this project we investigate the fundamental connections between spin waves, spin polarized electrons and photons, combining the three recently emerged research directions of magnonics, spintronics and photonics. This research is driven by the demand for new concepts, technologies and materials for information processing since, on one side, electronics is reaching its physical limit of speed due to waste heat generation and, on the other side, photonics lacks fast, electronic control on small length scales. Spin waves, being the fundamental dynamic excitations of ferromagnets with frequencies in the gigahertz to terahertz regime, offer the unique opportunity to merge the best aspects of spintronics and photonics opening new pathways for information processing. You can find a more detailed overview of our current research topics here.

Our methods cover for example time- and phase-resolved Brillouin light scattering microscopy (TR-µBLS), time-resolved magneto-optical Kerr microscopy (TR-µMOKE), a femtosecond-laser system, electrical detection via the (inverse) spin Hall effect (ISHE) as well as micromagnetic simulation.

Joining our group

If you are interested in joining our group (i.e. for a Bachelor, Master or PhD Thesis, as a research assistant or postdoc) see our open positions section for possible topics or directly contact Dr. Helmut Schultheiß. Exemplary topics are:

Interaction of spin waves and spin polarized currents

Using the spin degree of electrons and coherent transport of spin information is one of the grand challenges of condensed matter physics. Spin wave, which are also called magnons, are the fundamental exciation quanta of a ferromagnet and can interact with spin polarized currents. This interaction can be studied on a nanometer lengthscale using magneto-optical techniques such as Kerr-effect and Brillouin light scattering microscopy as well as electrical measurements based on the (inverse) spin Hall effect.

Magnon-Qubit Hybrid Systems

The frequency range of magnons in metallic ferromagnets perfectly matches the energy gap of varios crytal defects in diamond or SiC crystals. These defects host electronic states within the bandgap and thus are ideal two-level systems for studying quantum phenomena. We experimentally demonstrate a frequency downconversion of the applied microwave excitation which allows a pure-magnonic control of the spin qubit at previously inaccessible frequencies. Our results open new avenues for developing scalable hybrid quantum technologies while offering a testbed for exploring the convergence of nonlinear, threshold-activated systems with intrinsically linear quantum systems.