Electrical Transport Involving Evanescent States in III-V Semiconductors: The Role of Spin-Orbit-Coupling

• Applicant: Privatdozent Dr. Martin Wenderoth
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2007 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 40976498

Spin-dependent tunneling is of growing importance in spintronics. Fundamental properties of tunneling phenomena in solids are intensively investigated. The structure of the evanescent states is crucial in determining the tunneling scheme. Although the effect of spin-orbit-interaction (SOI) on the real part of the band structure is a well-established topic, its transfer to the complex part is - in semiconductor physics - at the very beginning and currently under discussion. This is even more amazing because theoretical works have predicted a strong impact of SOI on evanescent states indicating a high potential for spintronics. The goal of our project is a better understanding of the tunneling processes including spin orbit interaction and the exploration of possibilities to manipulate the carrier spin during tunneling by means of electric and magnetic fields based on a “huge” SOI. Complementary to widely used nanoscale devices like two dimensional barriers or quantum dots which e.g. provide energy dependent transmission probabilities we use scanning tunneling microscopy and spectroscopy to study evanescent states. This method gives atomic scale information of the spatial and directional dependence of electronic transport described in terms of complex band structures. Combining low temperature cross-sectional STM/STS with in situ electric and magnetic fields offers a new approach to this physics. Parallel, we are looking for macroscopic effects using magneto optical Kerr effekt (MOKE) to support the idea of strong SOI on evanescent states.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1285: Semiconductor Spintronics
• Participating Person: Professor Dr. Rainer G. Ulbrich