Quantum kinetic theory of ultrafast phenomena in diluted magnetic semiconductors

• Applicant: Professor Dr. Vollrath Martin Axt
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2014 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263274142

This project is devoted to theoretical studies of ultrafast phenomena in diluted magnetic semiconductor (DMS) which are targeted at advancing the understanding of basic physical processes in DMS such as spin and orbital-angular-momentum transfer on ultrafast time scales. We aim to identify quantum-kinetic mechanisms that are of interest for advanced technological applications, e.g., the coherent control of magnetic properties on short times. The specific objectives of the project are three-fold. First, to elucidate the competition of the spin-orbit interaction with RKKY-type exchange interactions in the spin transfer between free carriers and magnetic impurities. Second, to explore the coherent quantum control possibilities brought about by excitation with light with orbital angular momentum (twisted light) and intense single-cycle terahertz pulses. And finally, to investigate the role of the electron-electron interaction in the decoherence processes that limit the coherent manipulation of angular-momentum transfer in DMS. The methodic starting point is a recently developed quantum kinetic density matrix description of the exchange induced spin-transfer in DMS. This theory shall be extended to include additionally the spin-orbit and electron-electron interaction as well as the coupling to twisted light. If in the course of the project it turns out to be necessary, also non-equilibrium Green's function techniques may be used. The applicability of the newly developed extended equations shall be demonstrated by numerical studies that reveal the physical implications and allow for a comparison of the predictions with realistic (existing or proposed) experimental situations.

• DFG Programme: Research Grants