Dynamic Nuclear Polarization by optical Stark effect in periodically-pumped gallium arsenide

Abstract

Optical pump-probe time-and magnetic-field-resolved Kerr rotation measurements provide a window into the mechanisms that generate dynamic nuclear polarization in bulk gallium arsenide. Previously, we have reported an unexpected dependence of the direction of the nuclear polarization on the sweep direction of the applied external magnetic field. In this paper, we present numerical calculations based on a model for this nuclear polarization due to the optical orientation and optical Stark effect produced by a train of ultrafast optical pulses. We demonstrate the correspondence of the model to our experimental measurements for different laser wavelengths and magnetic field sweep rates. Finally, we show that the model reproduces the sweep direction dependence and provides an explanation for this behavior.

Interplay of spin mode locking and nuclei-induced frequency focusing in quantum dots

“…There, the influence of a positive and negative detuning on NIFF is discussed, but a different model is used for the spin dynamics. In another recent study by Dominguez et al [70], the optical Stark effect induced by detuned pulses turns out to be very important to accurately describe DNP in the system. A third relevant aspect is the inclusion of a finite pulse duration, which leads to a reduced efficiency of the pulse for large magnetic fields and can also lead to phase shifts for the resonances [10,59].…”