  We study the stability of two-domain spin structures in an ultra-cold gas of
magnetically trapped $^{87}$Rb atoms above quantum degeneracy. Adding a small
effective magnetic field gradient stabilizes the domains via coherent
collective spin rotation effects, despite negligibly perturbing the potential
energy relative to the thermal energy. We demonstrate that domain stabilization
is accomplished through decoupling the dynamics of longitudinal magnetization,
which remains in time-independent domains, from transverse magnetization, which
undergoes a purely transverse spin wave trapped within the domain wall. We
explore the effect of temperature and density on the steady-state domains, and
compare our results to a hydrodynamic solution to a quantum Boltzmann equation.
