During recent experiments, researchers at Princeton University were "completely surprised" to discover a behavior in an insulator that was previously believed to be unique to metals, NewAtlas reports.
The discovery hints at the existence of a new type of quantum particle, dubbed a neutral fermion by the Princeton physicists. They published their findings in the journal Nature.
Typically, metals conduct electricity and insulators do not. This is due to the fact that electrons are generally very mobile in metals, while the high resistance of insulators slows down this movement.
Due to the high movement of electrons in metals, they are able to exhibit a phenomenon known as quantum oscillations.
When electrons in metals are exposed to a magnetic field at very low temperatures, they are able to shift into a quantum state that causes resistivity oscillation in the material.
Until the recent discovery at Princeton, however, it was thought that this state was not achievable in insulators due to their high resistance.
Quantum oscillation in an insulator
The new study by the Princeton researchers details how they accidentally discovered quantum oscillation in an insulator made out of a material called tungsten ditelluride.
While measuring the resistivity of the material under a magnetic field they discovered the unusual behavior.
"This came as a complete surprise," Sanfeng Wu, senior author of the study explains in a press release. "We asked ourselves, ‘What’s going on here?’ We don’t fully understand it yet."
Possible new quantum particles
While the researchers noted that there is no current theory that can describe this phenomenon, they did come up with their own hypothesis.
The team believes it might not actually be the electrons themselves that are oscillating. Instead, the strong interactions in the material might be creating new quantum particles that exhibit the effect they observed.
The researchers called the hypothetical particles neutral fermions, as any particles moving through an insulator would have to have a neutral charge.
"If our interpretations are correct, we are seeing a fundamentally new form of quantum matter," says Wu. "We are now imagining a wholly new quantum world hidden in insulators. It’s possible that we simply missed identifying them over the last several decades."
The researchers say they will continue to study the possible existence of the so-called new quantum particles, neutral fermions with future experiments.