Electrons Free of Atoms Interact More Strongly With Each Other

From the study of an unusual two-dimensional electron system that is generated on the surface of low-temperature liquid helium, a RIKEN-led international research team has revealed that electrons free of atoms interact more strongly with each other than their counterparts in a semiconductor.

The work provides valuable insights into both electron interactions and thin films of so-called ‘two-dimensional free electron gases’, which have useful applications. Low-noise amplifiers in mobile phone base stations, for example, use the electrical characteristics of weakly interacting two-dimensional electron gases in thin-film semiconductor devices.

The strong electron interaction observed by the researchers was evident once the free electrons were excited into a higher energetic state by microwave radiation (Fig. 1). “As soon as the first electrons are in the higher state, the strong interaction between electrons in both states means that the energy difference between these two states changes as a result,” comments Denis Konstantinov from the research team.