Topological Insulators - GDR Meso

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Surface States of 3D Topological Insulators • The Z2 topological order in the bulk (band inversion induced by strong spin orbit) • Robust edge (surface) states : Dirac fermions (odd number) «strong» topological insulator, ν0 =1, not layered Z2 Top. Ins. Empty Top. Band Insulator E Filled Band mardi 3 janvier 12
Surface States of 3D Topological Insulators • The Z2 topological order in the bulk (band inversion induced by strong spin orbit) • Robust edge (surface) states : Dirac fermions (odd number) • First proposed candidate : Bi1-xSbx Fu and Kane PRB 76 (2007) «strong» topological insulator, ν0 =1, not layered • Second generation 3D Topological Insulators Bi2Se3, Bi2Te3, Sb2Te3, ... • Reference material : Bi2Se3 ‣ single Dirac cone at the surface, stoichiometric, large band gap : 0.3 eV • «Third generation» 3D Topological Insulators ‣ TlBiTe2, Bi2Te3 ·(GeTe)0.5 ‣ strained HgTe : Ideal material ? L. Molenkamp group, PRL (2011) T. Meunier et L. Lévy : cf talk by C. Bouvier How to probe experimentally these 3D Top. Insulators ? ‣ existence of surface states (Dirac fermions) : ‣ (spin resolved) ARPES ‣ STM ‣ transport ... problem : get rid of bulk contribution mardi 3 janvier 12 Checkelsky et al., PRL. 103, 246601 (2009) Zhang H. et al., Nat. Phys. 5, 438 (2009) ARPES of topological insulator First observation by D. Hsieh et al. (Z. Hasan group), Princeton/LBL, 2008. This is later data on Bi2Se3 from the same group in 2009: The states shown are in the “energy gap” of the bulk material--in general n
Page 1: Some Transport properties of Topolo
Page 5 and 6: Transport measurement on TI Bi2Se3
Page 7 and 8: Transport measurement on TI Bi2Se3
Page 9 and 10: Transport measurement on TI ‣ Bi2
Page 11 and 12: 2D Dirac Matter A B H = ~v F ( y .k
Page 13 and 14: Diffusion of 2D Dirac states • Tr
Page 15 and 16: Study of diffusion of 2D Dirac stat
Page 17 and 18: (Weak) Localization • Probability
Page 19 and 20: (Weak) Localization / Quantum trans
Page 21 and 22: Weak localization : Universality cl
Page 23 and 24: Weak localization : Universality cl
Page 25 and 26: Anderson Univ. classes and Topologi
Page 27 and 28: Anderson Univ. classes and Topologi
Page 29 and 30: Anisotropic Scattering of Dirac sta
Page 31 and 32: Anisotropic Scattering of Dirac sta
Page 33: Conclusion ‣ New playground for u

Topological Insulators - GDR Meso

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