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Dr. Stefano Chesi McGill University, Montreal, Canada |
Abstract: Spin-orbit interactions in the solid-state play a crucial role for coherent spin manipulation, topological insulators, and in the search for Majorana fermions. In this talk we investigate spin-polarized transport in quantum point contacts (QPCs) fabricated from GaAs two-dimensional hole gases. We show that several surprising observations of magnetic focusing experiments can be understood form the presence of a crossing point at finite momentum in the lowest two spin-subbands. The crossing point originates in one-dimension from a strong two-dimensional Rashba spin-orbit interaction, which for heavy-holes has a non-linear (cubic) dependence on momentum. This feature allows us to explain the anomalous behavior of the spin polarization filtered by the QPC. We also discuss how to remove the degeneracy at the crossing point with a magnetic field parallel to the channel or an asymmetric lateral confining potential. Controlling the magnitude of the spin-splitting affords a novel mechanism for inverting the sign of the spin polarization.
About the Speaker: Dr. Stefano Chesi received his Ph. D. in 2007 from Purdue University, USA, and from 2007 to 2011 performed postdoctoral research in the group of Prof. Daniel Loss (University of Basel, Switzerland). Currently, he is a Research Associate at McGill University, Montreal, Canada. His research area is theoretical Condensed Matter Physics, with a strong focus on spin-dependent phenomena and many-body correlations in semiconductors. Other interests include topologically protected models for storage of quantum information and solid-state implementations of quantum computing.
Date&Time: January 11, 2013 (Friday), 15:30–16:30
Location: 606 Conference Room
