Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 36: TR: Poster Session

TT 36.12: Poster

Donnerstag, 25. März 2010, 14:00–18:00, Poster A

Controlled ballistic electron beam propagation in a Rashba spin orbit split two dimensional electron gas — •Mathias J. Mühlbauer, Christoph Brüne, Elena G. Novik, Hartmut Buhmann, and Laurens W. Molenkamp — Physikalisches Institut (EP3), Universität Würzburg, 97074 Würzburg, Germany

For spintronic applications, systems with high spin orbit (SO) coupling strength provide a promising environment. There it should be possible to observe the electronic analogue of the birefringent effect for polarized light as proposed by M. Khodas et al. [1]. The beam polarization takes place at a junction between regions with different SO splitting. HgTe/HgCdTe quantum wells are the material of choice. Electron beam injection and detection can be provided by quantum point contacts (QPCs). However, the realization of QPCs in HgTe/HgCdTe structures is not trivial due to the narrow band gap and the presence of the Quantum Spin Hall Effect (QSHE) [2]. Here, we demonstrate that it is possible to fabricate QPCs using electron beam lithography and dry etching techniques and to control its transmission with a top gate electrode. The functionality of the devices is confirmed by measurements of conductance and electron beam collimation effect. The quantized conductance is the first demonstration for a HgTe based structure. We would like to note that the conductance sequence shows steps of e²/h indicating the influence of the Rashba SO splitting. We will present and discuss measurements on these devices.

[1] M. Khodas et al.,Phys. Rev. Lett. 92, 086602 (2004).

[2] M. König et al.,Science, 318, 766, (2007).