Electrons in a conductor usually behave like a gas: they dart around chaotically, collide, and don't hold formation. But if you spread them far apart and cool them down, their mutual repulsion can force them into place, like attendees in an overcrowded hall who settle into every other seat. This arrangement is called an electronic crystal, or Wigner crystal. In the new work, physicists have for the first time observed in detail how this order falls apart when heat increases or the magnetic field weakens.
The experiment used a film of VCl3 just one atomic layer thick on graphite. In a strong magnetic field, two electronic crystals formed simultaneously, with different lattice spacings and different resistance to heat. The first, with a record-high temperature and density for such a state, first transformed into an intermediate phase as the field weakened — electrons still held their rows, but the rows stretched in one direction, like a crowd that starts moving toward the exit but hasn't mixed. The second, less robust crystal melted differently: an anomalous electronic liquid emerged, in which density waves maintained the same period regardless of energy.
First-principles calculations confirmed that the two crystals arise because electrons transferred from the film to graphite occupy different energy bands. Thus, in a single sample, two scenarios of order destruction were observed: through an elongated intermediate phase and through a strange liquid with a fixed period. This provides a map of states where order and chaos alternate under the influence of quantum and thermal fluctuations.
The electronic crystal was first predicted by Eugene Wigner in 1934, but it took decades to observe it directly, the order turned out to be too fragile.