Vanishing Hall Coefficient in the Extreme Quantum Limit in Photocarrier-Doped SrTiO3

We have investigated the extreme quantum limit of photogenerated electrons in quantum paraelectric SrTiO3. This regime is distinct from conventional semiconductors, due to the large electron effective mass and large lattice dielectric constant. At low temperature, the magnetoresistance and Hall resistivity saturate at high magnetic field, deviating from conventional behavior. As a result, the Hall coefficient vanishes on the scale of the ratio of the Landau level splitting to the thermal energy, indicating the essential role of lowest Landau level occupancy, as limited by thermal broadening.