Scientists have observed a quantum fluid of electrons in graphene for the first time, showing near-perfect fluid behaviour and shedding light on a quantum physics puzzle.
Image Credit: JA Creatives/Shutterstock.comIn a collaborative effort, researchers at the Indian Institute of Science and Japan’s National Institute for Materials Science have captured an elusive fluid state in graphene. The study was published in Nature Physics, and attempts to answer the question of whether electrons behave like a perfect, frictionless fluid.
Atomic imperfections and impurities in materials has meant it is exceptionally difficult to explore this electron behaviour. However, the new study, with ultra-clean graphene samples, may have found a way around this.
It is amazing that there is so much to do on just a single layer of graphene even after 20 years of discovery.
Arindam Ghosh, Study Corresponding Author and Professor, Department of Physics, Indian Institute of Science
The researchers created exceptionally clean graphene samples and examined how they conduct both electricity and heat. What they found was surprising: the two types of conductivity were inversely proportional. When electrical conductivity rose, thermal conductivity dropped, and vice versa.
This relationship contradicts a well-known concept called the Wiedemann-Franz rule, which states that electrical and thermal conductivity values should be precisely related. In this case, the relationship broke down by a factor of more than 200 at low temperatures.
The researchers found that both charge and heat conduction in the graphene samples relied on a material-independent universal constant equal to the quantum of conductance, a basic value connected to the movement of electrons.
The unusual behaviour was most prominent near the “Dirac point,” a state where graphene behaves as neither a metal nor an insulator. At this point, electrons stop acting like individual particles and instead flow together as a collective, low-viscosity fluid. The fluid behaves similarly to water, but about a hundred times less viscous.
Since this water-like behavior is found near the Dirac point, it is called a Dirac fluid – an exotic state of matter which mimics the quark-gluon plasma, a soup of highly energetic subatomic particles observed in particle accelerators at CERN.
Aniket Majumdar, Study First Author and PhD Student, Department of Physics, Indian Institute of Science
The scientists also evaluated the viscosity of this Dirac fluid and discovered that it was the closest thing to a perfect fluid, minimally viscous.
The findings could make graphene a potential low-cost platform for laboratory investigations into high-energy physics and astrophysics issues such as black hole thermodynamics and entanglement entropy scaling.
From a technological standpoint, the presence of Dirac fluid in graphene has important applications in quantum sensors that are capable of amplifying very weak electrical signals and monitoring extremely weak magnetic fields.
Journal Reference:
Majumdar, A., et al. (2025) Universality in quantum critical flow of charge and heat in ultraclean graphene. Nature Physics. doi.org/10.1038/s41567-025-02972-z
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