Abstract
Sizable nuclear spin polarization is pumped in individual electron-charged dots in a wide range of external magnetic fields by circularly polarized optical excitation. We observe nuclear polarization of up to at corresponding to an Overhauser field of . We find a strong feedback of the nuclear spin on the spin pumping efficiency. This feedback, which is produced by the Overhauser field, leads to nuclear spin bi-stability at low magnetic fields of . We find that the splitting in magnetic field between the trion radiative recombination peaks markedly increases, when the Overhauser field in the dot cancels the external field. This counterintuitive result is shown to arise from the opposite contribution of the electron and hole Zeeman splittings to the optical transition energies.
- Received 17 December 2007
DOI:https://doi.org/10.1103/PhysRevB.77.165338
©2008 American Physical Society