Electrons behave like liquid and break fundamental law of physics

Energy

Technological Innovation Website Editorial Team - October 2, 2025

It's literally a flood—only of electrons, not water. [Image: IISC]

Connection between electricity and heat

Physics textbooks provide a very clear rule for metals, known as the Wiedemann-Franz law, which states that the values ​​of electrical conductivity and thermal conductivity must be directly proportional.

Or at least they should be.

But that's not what Aniket Majumdar and colleagues at the Indian Institute of Science documented. They observed a strong deviation from this law, by a factor of more than 200, demonstrating the decoupling of the mechanisms of electric charge and heat conduction.

The work addresses a central puzzle in quantum physics that remains unsolved: Could electrons behave like a perfect, frictionless fluid, with electrical properties described by a universal quantum number?

This unique property of electrons has been extremely difficult to detect in any material until now, due to the presence of atomic defects, impurities, and imperfections in test samples. Majumdar solved this problem by fabricating exceptionally pure graphene samples, which allowed him, for the first time, to trace how a 2D material, with an ordered crystalline structure like metals, conducts electricity and heat simultaneously.

To their surprise, the researchers discovered an inverse relationship between the two properties: As one value (electrical conductivity) increased, the other (thermal conductivity) decreased, and vice versa. And the variation was very large, representing a drastic violation of the Wiedemann-Franz law.

Electron liquid

The exotic behavior arose at the so-called "Dirac point," a precise electronic inflection point—achieved by adjusting the number of electrons in the material—where graphene is neither a metal nor an insulator. In this state, electrons cease to behave as individual particles and instead move together as a liquid, much like water, but a hundred times less viscous.

"Because this water-like behavior is found near the Dirac point, it is called a Dirac fluid—an exotic state of matter that mimics quark-gluon plasma , a soup of highly energetic subatomic particles observed in particle accelerators at CERN," Majumdar said.

And the decoupling between the mechanisms of electric charge and heat conduction is not a random event: Both charge and heat conduction, in this case, depend on a universal constant independent of the material, which is equal to the quantum of conductance, a fundamental value related to the movement of electrons.

Thus, say the researchers, the experiment shows that graphene functions as a low-cost platform for investigating very broad physics concepts, from entropy and quantum entanglement, on the smallest scales, to phenomena of high-energy physics and astrophysics, such as the thermodynamics of black holes, all in a laboratory environment.

From a technological point of view, the presence of Dirac fluid in graphene also presents significant potential for use in quantum sensors capable of amplifying electrical signals and detecting extremely weak magnetic fields.

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