Scientists have discovered a remarkable new phenomenon in rhombohedral graphene. This form of graphene, made of multiple ultra-thin layers stacked at specific angles, can host multiple superconducting states.
A team from MIT published their findings in the journal Nature. They found that in certain configurations, applying a magnetic field actually enhanced superconductivity rather than destroying it.
"It's very exotic that a magnetic field doesn't kill superconductivity, and instead it boosts it," said physicist Long Ju from MIT.
Normally, magnetic fields disrupt the electron pairs responsible for superconductivity. Here, researchers observed three distinct superconducting states. In one case, superconductivity only emerged when a magnetic field was applied.
The superconducting transition temperature increased from 55 millikelvin to approximately 90 millikelvin under these conditions. The material could also handle significantly more electrical current before superconductivity broke down.
The researchers theorize that in these specific configurations, electrons may pair up with others having the same spin alignment, making them resistant to magnetic disruption.
While these effects require ultra-cold temperatures and controlled lab environments, the discovery has potential implications for quantum computing. It could help stabilize qubits, the fundamental units of quantum information.
"This is how a simple physical material can exhibit so many different superconducting properties," Ju noted. The team plans to further investigate each superconducting state to understand the underlying mechanisms.