Best sighting yet of exotic crystals composed entirely of electrons
Exotic electronic states called Wigner crystals, in which mutual repulsion between electrons causes them to spontaneously form ordered arrangements, have been observed independently by two groups nearly 80 years after they were first predicted. The researchers argue their results, using a new type of spectroscopy, are more conclusive than previous observations.
Electrons in a material carry both potential energy from their mutual repulsion and kinetic energy arising from heat, much like atoms in a lattice. Whereas atoms can freeze relatively easily, the kinetic energy of electrons almost always dominates because electrons have so little mass they need little energy to move. Moreover, the electron density is normally too high for individual electrons to be distinguished amid their quantum uncertainty in position. The result is a homogeneous smear of electronic charge. In 1934, however, the great theoretical physicist Eugene Wigner predicted that electrons could form a crystalline solid – if their kinetic energy and density were reduced enough. external page->call_made