Transient quantum isolation and critical behavior in the magnetization dynamics of half-metallic manganites

We combine time-resolved pump-probe magneto-optical Kerr effect and photoelectron spectroscopy experi-ments supported by theoretical analysis to determine the relaxation dynamics of delocalized electrons in half-metallic ferromagnetic manganite La1−xSrxMnO3. We observe that the half-metallic character of La1−xSrxMnO3determines the timescale of both the electronic phase transition and the quenching of magnetization, revealing aquantum isolation of the spin system in double-exchange ferromagnets extending up to hundreds of picoseconds.We demonstrate the use of time-resolved hard x-ray photoelectron spectroscopy as a unique tool to single out theevolution of strongly correlated electronic states across a second-order phase transition in a complex material.