Physicists Have Discovered A New Form Of Matter Called Excitonium

An international team of physicists from the University of Illinois at Urbana-Champaign, University of California, Berkeley, and University of Amsterdam, claim they have finally proven the existence of a new form of matter called excitonium, almost 50 years after it was first theorized. Upon studying non-doped crystals of the transition metal dichalcogenide titanium diselenide (1T-TiSe2), the researchers were able to observe the material and its precursor soft plasmon phase called the “smoking gun” that proves the existence of this rare, exotic material. And surprisingly, they were able to reproduce the results 5 times on different cleaved crystals during the experiments.

Excitonium is a condensate, which exhibits macroscopic quantum phenomena, like a superconductor, or superfluid, or insulating electronic crystal. It consists of particles called excitons which are formed as a result of pairing of an escaped electron and the hole it leaves behind.

When an electron goes beyond its maximum energy level, it’s no longer bound to the nucleus of its atom and it’s considered to be ionized. When an electron temporarily occupies that energy state greater than its ground state, it’s considered to be in an excited state. So as it gets excited, it jumps over the energy gap to the otherwise empty conduction band and leaves a “hole” behind. The hole behaves as though it were a positively-charged particle itself and attracts the escaped electron. They then pair up to form the composite particle, a boson known as an exciton.

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