Electrical spin manipulation in SrTiO3/LaAlO3 3 /LaAlO 3 double quantum dots

The spin dynamics in two electron double quantum dots embedded in a two-dimensional electron gas at the interface between SrTiO3 3 and LaAlO3 3 is studied by an exact numerical solution of the time-dependent Schr & ouml;dinger equation in the context of the electric-dipole-spin-resonance experiment. On the basis of the three-band model of 3d d electrons localized at Ti ions on the square lattice, we analyze in detail the singlet- triplet transition induced by the ac electric field, in the magnetic field range close to the avoided crossing that appears as a result of the spin-orbit coupling. For symmetric double quantum dots the single-photon spin-flip transition is prohibited due to the parity symmetry, and the transition can occur only by the higher-order two-photon processes. For a weakly asymmetric system, when the first-order singlet-triplet transitions are released due to the parity symmetry breaking, the spin-flip transition has a character of the Rabi oscillations for a low electric field amplitude. As the amplitude is increased, the frequency of the transition is blueshifted (redshifted) for the magnetic field below (above) the single-triplet avoided crossing. For a sufficiently high magnetic field and high ac-field amplitude, the electric field drives the system across the avoided crossing, inducing the spin flip by the Landau-Zener-Stueckelberg-Majorana effect. Finally, the optimization of the geometrical parameters of the system with respect to the time of spin flip of its fidelity is also presented.