Supersonic phenomena and nanoelectronics

Freak waves, as well as other less striking localised excitations, occur in nature at every scale. Now, European researchers have found that these phenomena could play a significant role at the quantum scale in nanoelectronics.

Spontaneously localised excitations may either be pinned to a crystal lattice — known as discrete breathers — or alternatively may travel, and are then referred to as solitons or spontaneous solitary excitation waves. Researchers led by Manuel G Velarde, from the Pluridisciplinary Institute at the University Complutense of Madrid, clarified the differences between these two types of excitations through a computer simulation, following a strong initial external pulse on a single lattice unit.

The study authors focused on the relative influence of the forces leading to these excitations as a result of on-site and intersite vibrations (corresponding to individual lattice units and relative displacements of units, respectively). Under certain conditions, they found that the discrete breathers evolve into a genuine soliton, moving at supersonic speed within the lattice.

These findings confirm that solitons can be used as natural carriers of energy, matter or electric charge (in the latter case, by transferring the soliton-like motion to the charges, allowing them to ‘surf’ on the soliton wave). Meanwhile, discrete breathers are natural traps for energy and can also be used as electric charge carriers under certain conditions. The study results, published in the journal EPJ B, could lead to applications such as transistors with extremely low heat dissipation not using silicon.