“It is amazing that there is so much to do on just a single layer of graphene even after 20 years of discovery,” says Arindam Ghosh, Professor at the Department of Physics, IISc, and one of the corresponding authors of the study.
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To uncover this behavior, the team created exceptionally clean graphene samples and carefully measured how they conduct both electricity and heat. What they found was unexpected. Instead of increasing together, the two properties moved in opposite directions. As electrical conductivity rose, thermal conductivity dropped, and vice versa.
This result directly contradicts the Wiedemann-Franz law, a well-established principle that states 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.
This result directly contradicts the Wiedemann-Franz law, a well-established principle that states heat and electrical conduction in metals should be proportional.
Man, graphene is weird. It’s like each atom of carbon was actually a sandwich of
- a non-metal using the sp² orbitals, forming a neat lattice with electrons also neatly arranged into σ bonds
- a metal using the p orbitals that refused to hybridise, creating a huge π network of delocalised electrons
My guess is that the violation of the law is caused by this dichotomy.
