Observation of acoustic edge magnetoplasmons near the filling factor $\nu=1$

Investigation of acoustic edge magnetoplasma excitations in micrometer two-dimensional electron disks has been carried out. It has been shown that additional acoustic edge magnetoplasma modes associated with the existence of incompressible strips in the two-dimensional electron system caused by Zeeman spin splitting can appear in the system at temperatures below the Zeeman energy. The magnetic dispersion of the first “spin” branch of acoustic edge magnetoplasmons has been studied. It has been shown that this mode vanishes as the filling factor $\nu=1$ is approached. The dependence of the relative amplitude of acoustic edge magnetoplasmons on the filling factor has also been investigated.