Experimental Realization: Two-Pump Optical Scheme for Selective Electron-Nuclear Spin Interaction and Overhauser Field Strength

This work experimentally demonstrates the robustness of the theoretically developed two-pump optical scheme. Electron spin polarization is pumped in Si-doped GaAs by time- and field-resolved Kerr rotation (TRKR/FRKR) pump-probe spectroscopy in the Voigt geometry. The optical pulses are negatively detuned from resonance, thereby causing electron spin polarization to build up along the external magnetic field direction due to the Stark effect [1]. The electron spin polarization along the magnetic field dynamically interacts with the nuclear spin ensemble. This process is commonly referred to as dynamic nuclear polarization (DNP). The Overhauser field (i.e., the nuclear magnetic field) will begin to form as the degree of nuclear spin polarization increases by DNP. The strength of the Overhauser field directly affects the Larmor precession frequency of the electron spin system. Consequently, insight can be made into the strength of the electron-nuclear spin interactions and subsequent magnitude of the Overhauser field by observing the electron spins Larmor precession frequency via TRKR/FRKR measurements [2]. Preliminary two-pump experimental results will be outlined and analyzed with the theoretically developed two-pump model to demonstrate the model’s robustness [3].

[1] M. J. Dominguez, J. R. Iafrate, and V. Sih, Phys. Rev. B 101, 205203 (2020)

[2] M. J. Dominguez, J. R. Iafrate, and V. Sih, Phys. Rev. B 104, 235204 (2021)

[3] E. Kesto, A. Rodriguez, M. J. Dominguez, and V. Sih, In Progress