Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 24: Topological insulators: mostly interaction with magnetic fields (with MA/TT)

HL 24.2: Vortrag

Montag, 31. März 2014, 16:00–16:15, POT 081

Quantum Interferences of Dirac fermions in Bi2Se3 nanostructures — •Louis Veyrat, Joseph Dufouleur, Romain Giraud, Hannes Funke, Silke Hampel, Christian Nowka, Joachim Schumann, and Bernd Büchner — IFW-Dresden, Dresden, Germany

Recently discovered Z2 topological insulators (TIs) are ideally conducting at their interface only, where a gapless band structure forms. In a strong 3D TI, such as Bi2Se3, surface states are spin-chiral Dirac fermions with an odd number of Dirac cones. However, in real materials, the finite bulk conductivity often prevents the study of surface-state transport. We show that mesoscopic transport measurements can unambiguously reveal the specific properties of spin-chiral Dirac fermions in a Bi2Se3 nanostructure [1]. The quantum conductance of a nanowire exhibits Aharonov-Bohm oscillations which result only from surface-state transport. At very low temperatures, the temperature dependence of their amplitude unveils the quasi-ballistic nature of charge transport, which is the signature of the weak coupling of quasi-particles to their environment. Our results further reveal the weak scattering by structural disorder, giving another evidence of the specific nature of spin-chiral Dirac fermions in a strong 3D TI. Furthermore, new physics evidenced in the study of UCF in a nanowire, could be the signature of a perfectly transmitted mode in a nanowire geometry [2].

[1] J. Dufouleur et al., Phys. Rev. Lett. 110, 186806 (2013)

[2] J. Bardarson et al., Phys. Rev. Lett. 105, 156803 (2010)