A particle missed during the initial development of quantum theory has been found thanks to researchers’ exploration of the “material universe” .
An international team of researchers have theorised that a particle, called the type-II Weyl fermion, exists in a material known as tungsten ditelluride (WTe2), which the researchers liken to a “material universe” because it contains several particles, some of which exist under normal conditions in our universe and others that may exist only in specialized types of crystals.
These crystals can be grown in the laboratory, so experiments can be done to look for the newly predicted Weyl fermion in WTe2 and another candidate material, molybdenum ditelluride (MoTe2).
“Even more intriguing is the perspective of finding more ‘elementary’ particles in other condensed matter systems,” the researchers say.
“What kind of other particles can be hidden in the infinite variety of material universes? The large variety of emergent fermions in these materials has only begun to be unravelled.”
The researchers assume that the particle’s existence was missed by physicist Hermann Weyl, during the initial development of quantum theory 85 years ago, because it violated a fundamental rule called Lorentz symmetry that does not apply to the materials where the new type of fermion arises from.
In recent years, researchers have discovered that such a “material universe” could host all other particles of relativistic quantum field theory. Three quasiparticles, the Dirac, Majorana and Weyl fermions, were discovered in such materials, despite the fact that the latter two had long been elusive in experiments.
“One’s imagination can go further and wonder whether particles that are unknown to relativistic quantum field theory can arise in condensed matter,” says Princeton University associate professor of Physics B Andrei Bernevig.
“One may wonder,” Soluyanov said, “if it is possible that some material universes host non-relativistic ‘elementary’ particles that are not Lorentz-symmetric?”
The existence of the type-II Weyl fermion and the behaviour it exhibits suggests a range of potential applications, from low-energy devices to efficient transistors.
The full version of the researchers’ findings – Type II Weyl Semimetals – can be found in the journal Nature.