Theoretical Physics - From Outer Space to Plasma The physics of “flat” electrons
May 7, 2025
Dumitru Călugăru, a research fellow at Oxford, dives into the fascinating world of flat band materials. He explains how engineering these materials can unlock exotic phases of quantum matter. The conversation covers the importance of band topology and how strong electron interactions can change the behavior of electrons in unique ways. He also touches on the historical context of Landau’s Fermi liquid theory and discusses experimental breakthroughs that illuminate the potential of flat bands in superconductivity.
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Flat Electrons Create Exotic States
- Flat electrons are normal electrons slowed down in certain materials, creating exotic quantum states.
- Their slowed kinetic energy enhances interactions leading to phenomena like superconductivity and magnetism.
Breakdown of Fermi Liquid Theory
- Landau's Fermi liquid theory explains interacting electrons as quasiparticles with renormalized parameters.
- This theory breaks down when electron interactions dominate, especially in flat band systems.
Dominance of Interactions in Flat Bands
- In flat bands, kinetic energy is negligible and electron interactions dominate, reversing usual perturbation theory.
- The many-body problem in flat bands requires non-perturbative approaches.