Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 11: FS: Topological Defects in Electronic Systems (with TT)

MA 11.8: Topical Talk

Tuesday, March 23, 2010, 13:15–13:45, H20

Spin Hall effects in HgTe Quantum Well Structures — •Laurens W. Molenkamp — Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Recently, it was pointed out that inverted HgTe structures are topologically non-trivial insulators, in which the quantum spin Hall insulator state should occur. In this novel quantum state of matter, a pair of spin polarized helical edge channels develops when the bulk of the material is insulating, leading to a quantized conductance. I will present transport data provide very direct evidence for the existence of this third quantum Hall effect: when the bulk of the material is insulating, we observe a quantized electrical conductance. Further experiments, using non-local transport measurements, show that the charge transport occurs through helical edge channels. The spin polarization of the edge channels can be demonstrated in split gate devices that are partially in the insulting and partly in the metallic regime, making use of the occurrence of the non-quantized metallic spin Hall effect to convert the magnetic spin signal into an electrical one.