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Proceedings Paper

Topological phases in InAs1−xSbx: from novel topological semimetal to Majorana wire (Conference Presentation)
Author(s): Georg W. Winkler; QuanSheng Wu; Matthias Troyer; Peter Krogstrup; Alexey A. Soluyanov
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Paper Abstract

Superconductor proximitized one-dimensional semiconductor nanowires with strong spin-orbit interaction (SOI) are at this time the most promising candidates for the realization of topological quantum information processing. 1-6 In current experiments the SOI originates predominantly from extrinsic fields, induced by finite size effects and applied gate voltages. The dependence of the topological transition in these devices on microscopic details makes scaling to a large number of devices difficult unless a material with dominant intrinsic bulk SOI is used. Here we show that wires made of certain ordered alloys InAs1-xSbx have spin splittings up to 20 times larger than those reached in pristine InSb wires.7, 8

We consider a stable ordered CuPt-structure at x = 0.5 with alternating (111)-layers of As and Sb. Experimental evidence for the CuPt-ordering of InA0.5Sb0.5 exists.9-13 Furthermore, we find an inverted band ordering realizing a novel type of topological semimetall14-17 with triple degeneracy points.18 We identify the novel semimetal as having both properties of the established topological Dirac 19-21 and Weyl15, 22 semimetals, and thus the triple point can be seen as an interpolation of Dirac and Weyl points. Analog to the Dirac and Weyl semimetals we find surface Fermi arcs19, 21, 23-27 and anomalous transport in the presence of magnetic fields. 28-30

The band inversion can be avoided either by application of experimentally achievable strain or incomplete ordering making the CuPt-ordered InA0.5Sb0.5 a semiconductor with a large intrinsic linear in k bulk spin splitting in the conduction bands. Furthermore, we find large Landé g-factors for thin films of CuPt-ordered InA0.5Sb0.5, which is crucial for the realization of various Majorana scenarios.1, 2, 31, 32 In conclusion, the electronic properties of CuPt-ordered InA0.5Sb0.5 outperform all presently available Majorana platforms.

Paper Details

Date Published: 6 December 2016
PDF: 3 pages
Proc. SPIE 9931, Spintronics IX, 99313H (6 December 2016); doi: 10.1117/12.2239101
Show Author Affiliations
Georg W. Winkler, ETH Zürich (Switzerland)
QuanSheng Wu, ETH Zürich (Switzerland)
Matthias Troyer, ETH Zürich (Switzerland)
Peter Krogstrup, Univ. of Copenhagen (Denmark)
Alexey A. Soluyanov, ETH Zürich (Switzerland)

Published in SPIE Proceedings Vol. 9931:
Spintronics IX
Henri-Jean Drouhin; Jean-Eric Wegrowe; Manijeh Razeghi, Editor(s)

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