Topic: Physics

Scientists at IISc and NIMS have found that graphene can behave like a quantum fluid. This discovery opens up new possibilities for studying quantum phenomena.

Scientists have long been trying to understand how electrons move in perfect, frictionless materials. Now, researchers at the Department of Physics, Indian Institute of Science (IISc), and collaborators from the National Institute for Materials Science in Japan have achieved this goal with graphene.

Graphene is a single layer of carbon atoms arranged in a flat sheet. To study its properties, the team created exceptionally clean samples and measured how they conduct electricity and heat. What they found was unexpected: instead of increasing together, these two properties moved in opposite directions. This result directly contradicts the Wiedemann-Franz law, which states that heat and electrical conduction in metals should be proportional.

The researchers observed deviations from this law by more than 200 times at low temperatures, revealing a striking separation between how charge and heat move through the material. Despite this unusual split, the behavior is not random. Both types of conduction appear to follow a universal constant that does not depend on the material itself.

This remarkable effect occurs at a special condition known as the 'Dirac point', where graphene sits at a boundary between being a metal and an insulator. By adjusting the number of electrons, researchers can reach this precise state. At this point, electrons stop behaving like individual particles and move collectively, flowing like a liquid.

The team also measured how easily this fluid flows and found that its viscosity is extremely low, making it one of the closest realizations of a perfect fluid ever observed.

Why It Matters

This discovery could have practical implications for developing highly sensitive quantum sensors. Such devices could amplify extremely weak electrical signals and detect faint magnetic fields, opening up new technologies in sensing and measurement.

Key Facts

• Scientists at IISc and NIMS have found that graphene can behave like a quantum fluid.
• The discovery opens up new possibilities for studying quantum phenomena.
• Graphene is a single layer of carbon atoms arranged in a flat sheet.
• The team observed deviations from the Wiedemann-Franz law by more than 200 times at low temperatures.
• The Dirac point is where graphene sits at a boundary between being a metal and an insulator.

Key Terms

Wiedemann-Franz law

A well-established principle that states heat and electrical conduction in metals should be proportional.

Implications

This discovery could have practical implications for developing highly sensitive quantum sensors. Such devices could amplify extremely weak electrical signals and detect faint magnetic fields, opening up new technologies in sensing and measurement.