Mechanism of ultrafast spin-polarization switching in nanostructures

We consider time-dependent processes in the optically excited hybrid system formed by a quantum well (QW) coupled to a remote spin-split correlated bound state. The spin-dependent tunneling from the QW to the bound state results in the nonequilibrium electron spin polarization in the QW. The Coulomb correlations at the bound state enhance the spin polarization in the QW. We propose a mechanism for ultrafast switching of the spin polarization in the QW by tuning the laser pulse frequency between the bound state spin sublevels. Mn-doped core/multishell nanoplatelets and hybrid bound state-semiconductor heterostructures are suggested as promising candidates to prove the predicted effect experimentally. The obtained results open a possibility for spin polarization control in nanoscale systems.