Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 72: Quantum dots: Transport properties

HL 72.3: Vortrag

Mittwoch, 2. April 2014, 15:30–15:45, POT 251

Spin-Spectroscopy of InAs Quantum Dots Defined in Gated Nanowires — •Sebastian Heedt¹, Thomas Gerster¹, Paul Wenk², Stefan Kettemann³, Werner Prost⁴, Jürgen Schubert¹, Detlev Grützmacher¹, and Thomas Schäpers¹ — ¹Peter Grünberg Institute (PGI-9) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich, Germany — ²Institute for Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany — ³School of Engineering and Science, Jacobs University Bremen, 28759 Bremen, Germany — ⁴Solid State Electronics Department, University Duisburg-Essen, 47057 Duisburg, Germany

The aim of this study is to investigate spin coherence properties of quantum dots defined in InAs nanowires by multiple top-gates and high-k dielectrics. This way, accurate control over the local potential landscape inside the nanowire is achieved and the quantum dots are tuned to the few-electron regime. An external magnetic field applied perpendicular to the nanowire axis strongly affects the quantum dot energy levels. Hence, the electron g factor can be determined and two-electron states exhibit an avoided-crossing in dependence of the magnetic field. The resulting energy gap gives a measure for the spin relaxation length inside the InAs quantum dot, which is compared with results from weak antilocalization in phase-coherent transport measurements. Spin relaxation exhibits a strong dependence on external electric fields yielding a cross-over from weak antilocalization to weak localization. Also, it is substantially affected by the confinement.