The coupling of orbital and spin degrees of freedom is the source of many
interesting phenomena. Here, we study the electron dynamics in a quantum
billiard --a mesoscopic rectangular quantum dot-- with spin-orbit coupling
driven by a periodic electric field. We find that both the spatial and temporal
profiles of the observables demonstrate the transition to chaotic dynamics with
qualitative modifications of the power spectra and patterns of probability and
spin density. The time dependence of the wavefunctions and spin density
distributions indicates spin-charge separation {seen in the decay of the
spin-charge density correlators}. This new spin chaos effect can be
experimentally verified leading to a better understanding of the interplay
between spin and spatial degrees of freedom, relevant to fundamental and
applied quantum physics.Comment: 6 pages, 4 figure