The charge of a single electron, e, is defined as the basic unit of electric charge. Because electrons—the subatomic particles that carry electricity—are elementary particles and cannot be split, fractions of electronic charge are not normally encountered. Despite this, researchers at the University of Illinois at Urbana-Champaign have recently observed the signature of fractional charges ranging from e/4 to 2e/3 in exotic materials known as topological crystalline insulators.
The team of researchers, led by Illinois Mechanical Science and Engineering Professor Gaurav Bahl and Illinois Physics Professor Taylor Hughes, has been using ultra high frequency electric circuits to study topological insulators since 2017. Their recent measurement of fractional charge, appearing in the current issue of the journal Science, stems from the team’s theoretical work on crystalline insulators.