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

Edmund Harbord, Yasuhiko Arakawa, Satoshi Iwamoto, Chee Fong, Yasutomo Ota

Research output: Contribution to journalArticle (Academic Journal)peer-review

2 Citations (Scopus)
176 Downloads (Pure)

Abstract

Repeated injection of spin-polarized carriers in a quantum dot (QD) leads to the polarization of nuclear spins, a process known as dynamic nuclear spin polarization (DNP). Here, we report the 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. Dynamic nuclear spin polarization with p-shell carriers could open up avenues for further control to increase the degree of nuclear spin polarization in QDs.

Original languageEnglish
Article number125306
Number of pages7
JournalPhysical Review B
Volume93
Issue number12
DOIs
Publication statusPublished - 16 Mar 2016

Keywords

  • quantum dot
  • spintronics
  • nuclear spin

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