Puebla, J., Chekhovich, E.A., Hopkinson, M. orcid.org/0000-0002-8097-6913 et al. (4 more authors) (2013) Dynamic nuclear polarization in InGaAs/GaAs and GaAs/AlGaAs quantum dots under nonresonant ultralow-power optical excitation. Physical Review B, 88 (4). 045306. ISSN 2469-9950
Abstract
We study experimentally the dependence of dynamic nuclear spin polarization on the power of nonresonant optical excitation in two types of individual neutral semiconductor quantum dots: InGaAs/GaAs and GaAs/AlGaAs. We show that the mechanism of nuclear spin pumping via second-order recombination of optically forbidden (“dark”) exciton states recently reported in InP/GaInP quantum dots [E. A. Chekhovich et al., Phys. Rev. B 83, 125318 (2011)] is relevant for material systems considered in this work. In the InGaAs/GaAs dots this nuclear spin polarization mechanism is particularly pronounced, resulting in Overhauser shifts up to ∼80 μeV achieved at ultralow optical excitation power, ∼1000 times smaller than the power required to saturate ground state excitons. The Overhauser shifts observed at ultralow power pumping in the interface GaAs/AlGaAs dots are generally found to be smaller (up to ∼40 μeV). Furthermore in GaAs/AlGaAs we observe dot-to-dot variation and even sign reversal of the Overhauser shift which is attributed to the dark-bright exciton mixing originating from electron-hole exchange interaction in dots with reduced symmetry. Nuclear spin polarization degrees reported in this work under ultralow-power optical pumping are comparable to those achieved by techniques such as resonant optical pumping or above-gap pumping with high-power circularly polarized light. Dynamic nuclear polarization via second-order recombination of “dark” excitons may become a useful tool in single quantum dot applications, where manipulation of the nuclear spin environment or electron spin is required.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2013 American Physical Society. This is an author produced version of a paper subsequently published in Physical Review B. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Electronic and Electrical Engineering (Sheffield) The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 27 Sep 2016 13:46 |
Last Modified: | 28 Mar 2018 03:14 |
Published Version: | http://dx.doi.org/10.1103/PhysRevB.88.045306 |
Status: | Published |
Publisher: | American Physical Society |
Refereed: | Yes |
Identification Number: | 10.1103/PhysRevB.88.045306 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:102109 |