Title: Dynamics and transverse relaxation of an unconventional spin-rotation mode in a two-dimensional strongly magnetized electron gas,
Abstract: An unconventional spin-rotation mode emerging in a quantum Hall ferromagnet
due to excitation by a laser pulse is studied. This state, macroscopically
representing a rotation of the entire electron spin-system to a certain angle,
microscopically is not equivalent to a coherent turn of all spins as a
single-whole and is presented in the form of a combination of eigen quantum
states corresponding to all possible S_z spin numbers. Motion of the
macroscopic quantum state is studied microscopically by solving a
non-stationary Schroedinger equation and by means of a kinetic approach where
damping of the spin-rotation mode is related to an elementary process -
transformation of a 'Goldstone spin exciton' to a 'spin-wave exciton'. The
system exhibits a spin stochastization mechanism (determined by spatial
fluctuations of the g-factor) providing the damping - the transverse spin
relaxation, but irrelevant to a decay of spin-wave excitons and thus not
providing the longitudinal relaxation - recovery of the S_z number to its
equilibrium value.