Making the cleanest graphene ever
Researchers at the , have produced the cleanest graphene yet, allowing quantum phenomena to appear in magnetic fields as weak as the Earth鈥檚 own.
The breakthrough, reported in by a team led by Professor Andre Geim, was achieved by placing a sheet of graphene just three atoms below cleaner bulk graphite. This 鈥減roximity mirror鈥� cancels out unwanted electric fields, reducing disorder in graphene by a factor of 100.
"Think of it like creating the ultimate clean room, but for electrons," explains first author Dr Daniil Domaretskiy. "We鈥檝e removed almost all the 鈥榙irt鈥� that disrupts smooth flow of electric current. You can suddenly see effects that were hidden, like wiping clean a fogged-up window."
In quantum materials, disorder hides delicate effects and can prevent new physics from emerging. Researchers normally go to great lengths to remove impurities and minimise interference, but in graphene the team has now pushed this to an extreme: just one uncontrolled electron per 100 million carbon atoms remains across an entire device.
This record-low disorder means that electrons travel faster and further than ever before. Key benchmarks of material quality, such as Shubnikov鈥揹e Haas oscillations, are now visible at fields below 10 Gauss. The celebrated quantum Hall effect appears below 50 Gauss, far weaker than a fridge magnet.
The concept is straightforward: the nearby graphite acts like an electrical mirror, cancelling random electric fields in the graphene layer. The challenge was engineering the mirror close enough, three atoms apart, without damaging the graphene.
鈥淣ow that we know how to make things this clean, it opens the door to exploring phenomena that were out of reach,鈥� said co-author Dr Zefei Wu. 鈥淭his is just the beginning.鈥�
The team expects their 鈥榩roximity-mirror鈥� technique to become standard for probing quantum phenomena in two-dimensional materials, enabling new discoveries in superconductivity, magnetism and exotic quantum phases, which would all benefit from the ultraclean electronic conditions to clearly emerge.
The work involved collaborators from Lancaster University, the National University of Singapore, and the National Institute for Materials Science in Japan.
This research was published in the journal .
Full title: Proximity screening greatly enhances electronic quality of graphene
DOI: 10.1038/s41586-025-09386-0
The is a world-leading graphene and 2D material centre, focussed on fundamental research. Based at 麻豆传媒, where graphene was first isolated in 2004 by Professors Sir Andre Geim and Sir Kostya Novoselov, it is home to leaders in their field 鈥� a community of research specialists delivering transformative discovery. This expertise is matched by 拢13m leading-edge facilities, such as the largest class 5 and 6 cleanrooms in global academia, which gives the NGI the capabilities to advance underpinning industrial applications in key areas including: composites, functional membranes, energy, membranes for green hydrogen, ultra-high vacuum 2D materials, nanomedicine, 2D based printed electronics, and characterisation.