MIT physicists have turned a once-unthinkable scenario into reality by discovering a “chiral superconductor” that is also intrinsically magnetic. Even more remarkable, this quantum phenomenon was found in ordinary graphite, the same material commonly used in pencil lead.
The Hallmark Discovery: Magnetism Meets Superconductivity
For over a century, scientists believed that superconductivity and magnetism were fundamentally incompatible. Superconductors are known for expelling magnetic fields, a principle called the Meissner effect, and typically lose their superconducting qualities when exposed to strong magnetism.
Defying this rule, MIT researchers found that graphite with a rare “rhombohedral” staircase-like stacking of graphene layers can behave differently. When isolated and cooled to just 300 millikelvins above absolute zero, these thin graphite flakes conducted electricity with zero resistance.
The real breakthrough came when the team applied an external magnetic field. Instead of losing their superconducting state, these rhombohedral graphene flakes could be switched between two distinct superconducting phases, similar to flipping a magnetic switch.
This discovery of internal magnetism within a superconductor is unprecedented and challenges the conventional wisdom about these materials.
How Does Rhombohedral Graphene Do It?
Graphite consists of countless graphene sheets, but only specific regions with rhombohedral stacking exhibit this dual behavior. MIT’s team meticulously prepared microscopic flakes of this configuration, then cooled and tested them.
These flakes not only exhibited zero resistance at low temperatures but also demonstrated that their superconducting properties could be toggled by changing the direction of an applied magnetic field. During this switch, their resistance would momentarily spike, signaling a transition between two unique superconducting states.
Physicists attribute this behavior to the unique interactions among electrons in rhombohedral graphene. At extremely low temperatures, electrons slow enough to interact and pair up into “Cooper pairs,” gliding effortlessly through the material.
In this structure, electrons may cluster in the same quantum “valley,” pairing with both net momentum and orbital spin. This collective movement leads to an internal magnetism within the superconductor, a phenomenon described as chiral superconductivity.
Implications and Future Possibilities
This surprising discovery has been confirmed across multiple samples, highlighting its robustness. Chiral superconductors are especially intriguing for quantum computing, as they could pave the way for topological superconductors, materials capable of supporting stable quantum information processing.
The team’s findings underscore the potential for simple carbon-based materials to reveal new principles of physics and inspire novel technologies.
- Superconductivity allows for lossless electrical transmission.
- Magnetism in a superconductor opens revolutionary possibilities for electronics and quantum tech.
- Chiral superconductors could become key components in topological quantum computers.
- This research highlights the value in exploring “simple” materials for complex quantum effects.
A Paradigm Shift in Materials Science
MIT’s discovery fundamentally challenges established views on superconductivity and magnetism. Demonstrating that common graphite can harbor such exotic states, the research deepens our understanding of quantum materials and hints at transformative technologies ahead. As investigations continue, the scientific community anticipates new breakthroughs inspired by these unique superconductors.
Source: MIT News | Massachusetts Institute of Technology
MIT Physicists Unveil a Superconductor That Doubles as a Magnet