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Electronic transport in semiconductor nanostructures

Electronic transport in semiconductor nanostructures. Thomas Ihn ETH Zürich FS 17. After this lecture you know and understand…. ... Büttiker's view on the integer QHE … how interaction effects enter quantum Hall physics … the fractional quantum Hall effect phenomenology

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Electronic transport in semiconductor nanostructures

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  1. Electronic transport in semiconductor nanostructures Thomas Ihn ETH Zürich FS 17

  2. After this lecture you know and understand… • ... Büttiker's view on the integer QHE • … how interaction effects enter quantum Hall physics • … the fractional quantum Hall effect phenomenology • … the composite fermion view on the fractional quantum Hall effect

  3. Reading Chapter 16.3.5: edge channel reconstruction Chapter 16.3.6: QHE in graphene Chapter 16.4: fractional quantum Hall effect

  4. Last week Integer quantum Hall effect Landau quantization Quantum Mechanics

  5. Chiral edge states electrons propagate along edge (conducting) electrons localized in orbits (insulating) classical quantum electrons localized in the bulk and perfectly transmitting at the edge

  6. Transition between plateaus Integer quantum Hall effect between plateaus on plateaus

  7. Localized states in the bulk of a 2DEG magnetic field: B = 12 T, n = 1 – 2 Hashimoto, 2008 InSb(Cs) surface 2DEG

  8. Integer quantum Hall effect in graphene GaAs g=2 Berry phase 0 SL-Graphene g=2 (valley)+2 (spin) Berry phase p BL-Graphene g=2 (valley)+2 (spin) double degeneracy for zero energy LL Berry phase 2p

  9. Integer quantum Hall effect in graphene bi-layer graphene missing plateau at CNP single-layer graphene "half-integer QHE" charge neutrality point charge neutrality point manifestation of Berry phase p manifestation of Berry phase 2p

  10. Quantum Hall effect in graphene at room temperature K.S. Novoselov et al, Science 315, 1379 (2007)

  11. Reconstruction of edge channels

  12. Fractional quantum Hall effect

  13. Nobel prize in physics 1998 “…For their discovery of a new form of quantum fluid with fractionally charged excitations”

  14. The discovery

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