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HL: Fachverband Halbleiterphysik

HL 14: Poster: Two-Dimenaional Materials and Topological Insulators

HL 14.11: Poster

Montag, 20. März 2017, 14:00–18:00, P2-OG3

Possible topological insulator / superconductor interfaces for the investigation of Majorana excitations: (Bi_1−xSb_x)₂Te₃ and FeSe — •Philipp Küppers¹, Jens Kellner¹, Markus Eschbach², Martin Lanius³, Marcus Liebmann¹, Lukasz Plucinski², and Markus Morgenstern¹ — ¹II. Physikalisches Institut B RWTH Aachen University — ²PGI 6 Forschungszentrum Jülich — ³PGI 9 Forschungszentrum Jülich

Proximity induced s-type superconductivity (SC) in a topological insulator (TI) can lead to spinless, p-type superconductivity, which is the main ingredient for the creation of Majorana excitations (ME). To prove the existence of such quasi particles within the vortex of a type II SC grown on top of a TI with STS, two requirements have to be fulfilled. The Fermi energy E_F of the system has to be close to the Dirac point energy E_D of the TI and the superconducting gap has to be large in order to differentiate the ME from conventionally excited states within the vortex.

We present a method of tuning E_D with respect to E_F within 10 meV in the ternary TI (Bi_1−xSb_x)₂Te₃ by variation of the Sb concentration x [1]. We show first ARPES measurements of the band structure of the SC FeSe grown on SrTiO₃. Methods of inducing high temperature SC in FeSe are also presented.

[1] Jens Kellner et al., Appl. Phys. Lett. 107, 251603 (2015)