  Optical fields with orbital angular momentum (OAM) interact with medium have
many remarkable properties with its unique azimuthal phase, showing many
potential applications in high capacity information processing, high precision
measurement etc. The dephasing mechanics of optical fields with OAM in an
interface between light and matter plays a vital role in many areas of physics.
In this work, we study the transverse azimuthal dephasing of OAM spin wave in a
hot atomic gas via OAM storage. The transverse azimuthal phase difference
between the control and probe beams is mapped onto the spin wave, which
essentially results in dephasing of atomic spin wave. The dephasing of OAM spin
wave can be controlled by the parameters of OAM topological charge and beam
waist. Our results are helpful for studying OAM light interaction with matter,
maybe hold a promise in OAM-based quantum information processing.
