Edge magnetoplasma-like resonance in two-dimensional electrons on the surface of 3He–4He liquid mixtures

We have observed unexpected resonance phenomena in two-dimensional electron system formed on the free surface of dilute View the MathML source–View the MathML source liquid mixtures (with View the MathML source concentrations up to 21%), in a Corbino conductivity measurement. The resonances are observed only on the mixture surfaces, and were not observed both on pure View the MathML source and pure View the MathML source. The resonance frequency is inversely proportional to the magnetic field applied perpendicular to the electron sheet. This property is quite similar to the characteristics of edge magnetoplasmons (EMPs) or inter-edge magnetoplasmons (IEMPs), although the resonance frequency is much smaller than the ordinary EMPs frequencies. The resonances are altered by tilting the electrodes. These results suggest that the inhomogeneity in the electron density on a macroscopic scale is induced by adding a small amount of View the MathML source into liquid View the MathML source (possibly due to the growth of View the MathML source surface layers), and that the IEMPs propagate at the boundary between two regions with different electron densities.