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Topological Insulators

Topological Insulators

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Topological Insulators

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  1. Topological Insulators Effects of spin on transport of electrons in solids

  2. Most figures from:

  3. SPIN • Mott insulators • Rashba effect • Superconductivity • Quantum information and computation

  4. Topological insulator • Exhibits insulating behaviour in the bulk but has conducting edge or surface states • So far the only models exploit spin-orbit interactions • is generally related to introducing a time-reversal-symmetry breaking interaction, as is the case for SO. • Existence established in some systems from ARPES experiments

  5. Rashba effect • Spin-orbit coupling-like potential 

  6. SO in graphene

  7. Cases • A gap is produced • For the gap is • Quantized Hall conductivity: • BUT! It will vanish for

  8.  Gapless edge states • At the edges opposite spins travel opposite directions. (Kane et al) • At low energy

  9. Use like wires

  10. Observation • Graphene SO effects very small, hard to observe • Bi1-xSbx Observed! Surface states instead of edge states • Using ARPES

  11. Promises • Topological states robust to perturbation • Stable qubits for Quantum Computation • Dissipation-less spin current transport good for Spintronics new SuperConductivity-like effects to be observed, I presume. Not literally.