In a new article published in Physical Review Letters, a team from the Institute of Solid State Physics, led by Carsten Held, spoke about a very interesting discovery. “Imagine that the atoms are located inside the crystal within a certain scheme, and with each atom there is a moving electron. However, when studying a crystal, you understand that one specific atom does not have an electron – we call this a “hole,” Held explains.
Such “electronic holes” most often turn out to be quasiparticles – phenomena that appear only inside solids. For example, such “holes” allow electrons to pass through semiconductors. The “hole” itself is considered to be an independent quasiparticle or, in some cases, a part of a more complex quasiparticle.
Held’s team was lucky to discover a new, previously unknown quasiparticle, which physicists nicknamed the “pi-ton”. It includes two electrons and two holes, which makes it quite large among their own kind. Piton is activated by photon absorption. By the way, the name is a fun word game that has a mathematical basis: π-tones inside the structure are always 180 degrees opposite to their neighbors, and 180 degrees is just the “pi angle measured in radians,” as physicists themselves assure.
Experiments with quasiparticles can advance modern physics and our understanding of the properties of various materials to a qualitatively new level, however, this requires specific and very difficult conditions. So, in 2016, scientists tried to use supercooled quantum gas, but for pitons this may not be enough. So now the team is busy inventing ways to transfer the results of computer simulations to a real, physical model.