Analysis of the coupled electron-ripplon oscillations resonance spectra in the Wigner solid at different temperatures and modeling of the excitation process
V.E. Syvokon and I.V. Sharapova
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Nauky Ave., Kharkiv 61103, Ukraine
Received December 12, 2017
Spectra of the coupled electron-ripplon oscillations in Wigner solid over superfluid helium are studied experimentally at different temperatures and excited voltages which lead to the spectra deformation. It is shown that at all temperatures increasing the exciting voltage lead to appearing the non-axisymmetrical oscillation modes. That can be due to distortions of the crystal lattice. The possibility of excitation of the non-axisymmetrical modes is demonstrated with the molecular dynamics simulation. At some fixed frequencies amplitudes of the response on the external excitation are measured depending on excitation voltage. Amplitude jumps are found at the critical voltages. Using the Lindemann criteria a correlation between the critical voltage and stability limit of crystal lattice is found. It is concluded that the dynamical melting of the electron crystal occurs at the critical voltage.
PACS: 73.40.–c Electronic transport in interface structures;
Key words: Wigner crystal, superfluid helium, two-dimensional system, resonance spectra, electron-ripplon oscillations.
Published online: March 27, 2018