Experimentelle Physik 2b
Spin Dynamics and Spin Transport:
The idea of exploiting the spin degree of freedom for information processing initialized huge efforts to explore mechanisms of spin injection and schemes to investigate spin dynamics in semiconductors and nanostructures. Optical spectroscopy with femtosecond laser pulses provides a unique tool to investigate such phenomena. On the one hand side, spins can be optically prepared using circularly polarized laser pulses, i.e., by exploiting the selection rules for optical interband transitions. On the other hand, the dynamical magnetization associated with optically oriented electron spins can be directly measured via the Faraday and/or Kerr effect. In addition optical microscopy techniques offer the advantage of spatial resolution on the micrometer length scale. This additional spatial resolution provides, e.g., insight into coherent spin rotations related to spin-orbit interactions during charge carrier transport.
Within our research group we have developed profound expertise to investigate the spatio-temporal evolution of optically injected spin distributions on the length and timescales of micrometers and picoseconds, respectively. Many of the ongoing research activities in this field are part of the ICRC – TRR 160 “Coherent manipulation of interacting spin excitations in tailored semiconductors” (Dortmund/St. Petersburg). Current experiments are related to the following subjects:
- spin injection into indirect semiconductors such as germanium
- electrical tuning of electron spin coherence and spin-orbit interactions in GaAs based two-dimensional electron gases
- spin diffusion and spin-orbit interactions in CdTe quantum wells
- spin diffusion in novel monolayer materials
Ultrafast and Nonlinear Optics of Semiconductors and Nanostructures:
Semiconductors and semiconductor-based nanostructures typically exhibit large optical nonlinearities which are often further enhanced by electronic resonances. On the one hand side these nonlinearities can be directly exploited for nonlinear optical processes such as two-photon absorptions and frequency conversions. On the other hand the strong nonlinear response can be used for the analysis of carrier dynamics after ultrafast photoexcitation. Both approaches rely on the use of modern femtosecond laser pulses with typical peak powers in the MW range. Many of the ongoing research activities in this field are part of the ICRC – TRR 142 “Tailored Nonlinear Photonics: From Fundamental Concepts to Functional Structures” (Paderborn/Dortmund). Current experiments are related to the following topics:
- two-photon absorptions in optically excited semiconductors
- intersubband physics in GaN/AlN heterostructures
- nonlinear optical response of VO2 nanocrystals
Current offers for Bachelor-, Master- or PHD-theses
Please contact Prof. M. Betz if you are interested in thesis work on these topics.
Contact
- Prof. Dr. Markus Betz
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Location & approach
The campus of TU Dortmund University is located close to interstate junction Dortmund West, where the Sauerlandlinie A 45 (Frankfurt-Dortmund) crosses the Ruhrschnellweg B 1 / A 40. The best interstate exit to take from A 45 is "Dortmund-Eichlinghofen" (closer to Campus Süd), and from B 1 / A 40 "Dortmund-Dorstfeld" (closer to Campus Nord). Signs for the university are located at both exits. Also, there is a new exit before you pass over the B 1-bridge leading into Dortmund.
To get from Campus Nord to Campus Süd by car, there is the connection via Vogelpothsweg/Baroper Straße. We recommend you leave your car on one of the parking lots at Campus Nord and use the H-Bahn (suspended monorail system), which conveniently connects the two campuses.
TU Dortmund University has its own train station ("Dortmund Universität"). From there, suburban trains (S-Bahn) leave for Dortmund main station ("Dortmund Hauptbahnhof") and Düsseldorf main station via the "Düsseldorf Airport Train Station" (take S-Bahn number 1, which leaves every 20 or 30 minutes). The university is easily reached from Bochum, Essen, Mülheim an der Ruhr and Duisburg.
You can also take the bus or subway train from Dortmund city to the university: From Dortmund main station, you can take any train bound for the Station "Stadtgarten", usually lines U41, U45, U 47 and U49. At "Stadtgarten" you switch trains and get on line U42 towards "Hombruch". Look out for the Station "An der Palmweide". From the bus stop just across the road, busses bound for TU Dortmund University leave every ten minutes (445, 447 and 462). Another option is to take the subway routes U41, U45, U47 and U49 from Dortmund main station to the stop "Dortmund Kampstraße". From there, take U43 or U44 to the stop "Dortmund Wittener Straße". Switch to bus line 447 and get off at "Dortmund Universität S".
The AirportExpress is a fast and convenient means of transport from Dortmund Airport (DTM) to Dortmund Central Station, taking you there in little more than 20 minutes. From Dortmund Central Station, you can continue to the university campus by interurban railway (S-Bahn). A larger range of international flight connections is offered at Düsseldorf Airport (DUS), which is about 60 kilometres away and can be directly reached by S-Bahn from the university station.
The H-Bahn is one of the hallmarks of TU Dortmund University. There are two stations on Campus Nord. One ("Dortmund Universität S") is directly located at the suburban train stop, which connects the university directly with the city of Dortmund and the rest of the Ruhr Area. Also from this station, there are connections to the "Technologiepark" and (via Campus Süd) Eichlinghofen. The other station is located at the dining hall at Campus Nord and offers a direct connection to Campus Süd every five minutes.
The facilities of TU Dortmund University are spread over two campuses, the larger Campus North and the smaller Campus South. Additionally, some areas of the university are located in the adjacent "Technologiepark".
Site Map of TU Dortmund University (Second Page in English).