By Victoria Corless
Scientists studying “magic-angle” graphene have captured the clearest evidence yet of the electronic signature behind its superconductivity, cutting through years of speculation about what drives its exotic behavior.
“When superconductivity was first discovered in magic-angle graphene, it was surprising,” says Jeong Min Park of Princeton University. “Graphene by itself was not a superconductor, yet simply twisting layers turned it into one.”
Magic-angle graphene is created by stacking two or more layers of graphene and twisting them relative to each other by about 1°. At this “magic angle,” electrons slow dramatically, increasing their interactions and enabling entirely new states of matter.
“When this happens, the electrons interact with each other much more strongly, and this gives rise to new behaviours that don’t exist in the individual layers,” Park explains.
A Material of Many Personalities
A defining feature of magic-angle graphene is its tunability. With small applied voltages — a technique called gating — the same device can be switched between behaving as a superconductor, an insulator, or even a magnetic material.
“One piece of magic-angle graphene behaves like thousands of different materials you can dial between,” says Park.
However, this versatility also creates complexity: many electronic states lie close together, causing overlapping signals that make it difficult to isolate the one responsible for superconductivity.
“This complexity is a big reason why its superconductivity has remained such an intriguing mystery,” Park notes.
Cracking the Puzzle With Complementary Techniques
To unravel the mystery, Park and collaborators in Pablo Jarillo-Herrero’s group at MIT combined tunnelling spectroscopy with traditional transport measurements to directly link a specific electronic gap to the superconducting state.
“Each experimental technique revealed a different piece of the puzzle,” Park explains.
“Transport measurements tell us when electricity flows without resistance… Tunnelling spectroscopy shows the energy structure of the electrons directly, and allows us to potentially see the superconducting gap.”
Their approach revealed two distinct energy scales:
- A small, low-energy gap that disappears at a critical temperature and magnetic field — the true superconducting gap.
- A larger pseudogap, which may indicate a precursor state where electron pairs have formed but superconductivity hasn’t fully emerged, or another electronic process that supports the onset of superconductivity.
“This observation fundamentally challenges the simpler, single-gap model,” says Antonio Castro Neto of the National University of Singapore, who was not involved in the work. “It provides the clearest evidence yet that superconductivity in this material is ‘unconventional,’ likely involving electron pairs with a more complex structure.”
Implications for Future Quantum Technologies
Beyond resolving a long-standing question, the findings lay groundwork for designing new quantum materials that could enable next-generation quantum electronics.
“Magic-angle graphene hosts a whole zoo of quantum phases,” Park says.
This rich landscape positions it as a promising candidate for quantum electronic circuits.
Still, practical applications remain distant.
“We are far away from practical applications,” Castro Neto cautions.
“Major hurdles remain, including the extremely low operating temperature, material stability issues and limited current capacity. The value of this discovery is primarily in fundamental science.”
Reference
J. M. Park et al., Science (2025). DOI: 10.1126/science.adv8376
Source: Chemistry World
