Nearly 50 years after it was first theorized, physicists claim they’ve finally proven the existence of a new form of matter, known as ‘excitonium.’
Excitonium is made up of particles known as excitons, which are made from an escaped electron and the hole it left behind.
In the new experiments, the researchers say they were able to observe the material and the precursor phase, which is said to be the ‘smoking gun’ proof of its existence.
When an electron gets excited and ‘jumps’, it leaves behind a hole.
And, this hole can behave as though it were a particle itself, with a positive charge.
As it has a positive charge, the hole attracts the electron, pairing them to form a composite particle, or boson, known as an exciton.
In the new experiments, the researchers studied non-doped crystals of the transition metal dichalcogenide titanium diselenide (1T-TiSe2).
According to the team from the University of Illinois College of Engineering, they were able to reproduce the results five times on different cleaved crystals.
Previous efforts have struggled to distinguish the material from what’s known as a Peierls phase, which is unrelated but shares the same symmetry as exciton formation.
To uncover the elusive form of matter, the researchers developed a new technique called momentum-resolved electron energy-loss spectroscopy (M-EELS), which is more sensitive to excitations than other methods.