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arXiv · 1601.03480

P-shell carriers assisted dynamic nuclear spin polarization in single quantum dots at zero external magnetic field

C. F. Fong·Y. Ota·E. Harbord·S. Iwamoto·Y. Arakawa
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Abstract

Repeated injection of spin polarized carriers in a quantum dot leads to the polarization of nuclear spins, a process known as dynamic nuclear spin polarization (DNP). Here, we report the first observation of p-shell carrier assisted DNP in single QDs at zero external magnetic field. The nuclear field - measured by using the Overhauser shift of the singly charged exciton state of the QDs - continues to increase, even after the carrier population in the s-shell saturates. This is also accompanied by an abrupt increase in nuclear spin buildup time as p-shell emission overtakes that of the s-shell. We attribute the observation to p-shell electrons strongly altering the nuclear spin dynamics in the QD, supported by numerical simulation results based on a rate equation model of coupling between electron and nuclear spin system. DNP with p-shell carriers could open up avenues for further control to increase the degree of nuclear spin polarization in QDs.

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C. F. Fong, Y. Ota, E. Harbord, S. Iwamoto, Y. Arakawa. 2016-01-15. P-shell carriers assisted dynamic nuclear spin polarization in single quantum dots at zero external magnetic field. https://doi.org/10.1103/physrevb.93.125306

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