In the world of quantum materials, where particles exhibit strange and unpredictable behaviors, researchers have found that an old law still holds true. The law, known as the Lieb-Schultz-Mattis theorem, states that certain types of quantum systems cannot have an energy gap between their ground state and the first excited state.

This theorem has been known for over 40 years, but its implications for quantum materials are still being explored. In a new study, researchers at the University of California, Berkeley, and the University of Colorado Boulder have shown that the Lieb-Schultz-Mattis theorem can be used to understand the properties of a class of quantum materials known as Kitaev materials.

Kitaev materials are named after the Russian physicist Alexei Kitaev, who first proposed their existence in 2006. These materials are characterized by their strong spin-orbit coupling, which is the interaction between the spins of electrons and their orbital motion. This interaction gives rise to a number of unusual properties, including the ability to host Majorana fermions, which are quasiparticles that behave like their own antiparticles.

In their study, the researchers showed that the Lieb-Schultz-Mattis theorem can be used to explain the existence of Majorana fermions in Kitaev materials. They also showed that the theorem can be used to predict the properties of other Kitaev materials that have not yet been discovered.

These findings are a significant step forward in the understanding of quantum materials. They provide a new tool for researchers to use to design and engineer materials with specific properties. This could lead to the development of new technologies, such as quantum computers and spintronic devices.

The study is published in the journal Physical Review Letters.