Résumé
We develop a method of non-perturbative optical control over adiabatic remagnetisation of the nuclear spin system in semiconductors and apply it to study nuclear spin thermodynamics in GaAs microcavities. The nuclear spin system is found to exactly follow the predictions of the spin-temperature theory, despite the quadrupole interaction that was earlier reported to disrupt nuclear spin thermalisation [2]. These findings open a way to deep cooling of nuclear spins in semiconductor structures, with a prospect of realisation of nuclear spin-ordered states for high fidelity spin-photon interfaces.