At the University of Illinois, scientists received the first practical proof of the existence of excitons: a stable state of bosons, which under certain conditions form a fundamentally new form of matter And the term “exciton” was derived by Bert Halperin in the 1960s, but so far all this has been in the field of theoretical physics.
The world at the quantum level is very unusual: if an electron is excited at the edge of the valence band, he can move to a hole in the valence region, which becomes a quasiparticle, whose charge is positive, and the electron is negative – this pair is attracted and a boson is produced.To be more precise, this particular boson is called an “exciton,” and their array environment “excitonium”.
Physicists Anshul Kogar and Mindy Rack used the technology of spectroscopy of energy losses in the pulsed mode. They investigated crystals of the dichalcogenide dichalcogenide of titanium diselenide 1T-TiSe2, which were cooled to 190 degrees Kelvin (-83 ° C). As it approached this temperature, the metal entered the rarest state of the soft plasmon – the phase that precedes the appearance of excitonium.
And although the coveted new form of the substance itself has not yet been obtained, the measurements data convincingly prove – it is possible. There are just a few steps left. From the field of theoretical physics, scientists turned to practical. And although they can not predict what benefits can be derived from exciton at this stage, the very work with it will trigger the development of quantum physics.