RKKY Interactions on Dirac Surfaces by Herbert A Fertig

RKKY Interactions on Dirac Surfaces by Herbert A Fertig

International Centre for Theoretical Sciences via YouTube Direct link

Topological crystalline insulators TCI

19 of 24

19 of 24

Topological crystalline insulators TCI

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RKKY Interactions on Dirac Surfaces by Herbert A Fertig

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  1. 1 RKKY Interactions on Dirac Surfaces
  2. 2 Outline
  3. 3 Effective spin-spin interaction
  4. 4 Another completely equivalent approach: second order perturbation theory
  5. 5 RKKY Interactions in Graphene: A Paradigms for Dirac Surfaces
  6. 6 3. Electron wavefunctions are helical
  7. 7 4. Different possible locations for spin impurities: sd exchange coupling to multiple sites possible
  8. 8 So AA response is different than AB response
  9. 9 Strong local antiferromagnetic correlations from single particle physics
  10. 10 Numerical check: graphene sheet with periodic boundary conditions nanotube
  11. 11 Can we induce ferromagnetism in graphene? Need to break symmetry between sublattices. One way: use strain!
  12. 12 Problem: Breakdown of second order perturbations theory
  13. 13 Hilbert Space of states in LLL: M angular momentum states
  14. 14 Relative angle
  15. 15 Remaining Landau levels handled by perturbation theory:
  16. 16 Mean-field theory for RKKY interactions in strained graphene: Pairwise RKKY interaction = LLL nonperturbative part + 2nd order perturbative part
  17. 17 Net Moment
  18. 18 Dirac Surfaces on Topological Insulators
  19. 19 Topological crystalline insulators TCI
  20. 20 In topological regime....For 1 11 surface: Dirac points present at I and M 3 of these points
  21. 21 Slab geometry:total free energy computed for different orientations
  22. 22 Many thanks to ....
  23. 23 Summary
  24. 24 Q&A

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