Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 51: Topological Insulators (joint session DS, HL, MA, O, TT, organized by MA)

TT 51.3: Talk

Wednesday, March 22, 2017, 15:30–15:45, HSZ 401

Enhanced Mobility of Spin-Helical Dirac Fermions in Disordered 3D Topological Insulators — Joseph Dufouleur¹, Louis Veyrat¹, Bastien Dassonneville¹, Christian Nowka¹, Silke Hampel¹, Pavel Leksin¹, Barbara Eichler¹, Oliver G. Schmidt¹, Bernd Büchner¹, and •Romain Giraud^1,2 — ¹IFW, Dresden, Germany — ²INAC-SPINTEC, Grenoble, France

We reveal the enhanced transport length of 2D spin-helical Dirac fermions in highly-disordered 3D topological insulators, due to anisotropic scattering, by electrical transport measurements of Bi₂Se₃ nanostructures [1]. By comparing the quantum mobility, related to the electronic mean-free path, to the mobility obtained from trans-conductance measurements, related to the transport length (backscattering), we evidence the long-range nature of the scattering potential for surface Dirac fermions and some limitation due to a residual bulk/surface coupling. In wide nanostructures, it is shown that the long phase coherence length results from the enhanced diffusion constant, in very good agreement with results obtained from previous studies of the weak anti-localization [2]. Our work suggests that the spin-flip length (l_sf ≈ l_tr) could reach the micron size in materials with a reduced bulk doping, which reveals the true potential for building functionalized spintronic and ballistic electronic devices out of disordered 3D topological insulators.

[1] J. Dufouleur et al., Nano Lett. 16, 6733 (2016)

[2] Z. Li et al., Phys. Rev. B 91, 041401 (2015)