Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 101: Transport - Poster Session

TT 101.43: Poster

Thursday, April 3, 2014, 15:00–19:00, P2

Stability of Majorana metals — •Kevin O’Brien and Simon Trebst — Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany

The topological nature of exotic quantum states with non-Abelian vortices, such as p_x + i p_y superconductors, the Moore-Read quantum Hall state or certain heterostructures of topological insulators and s-wave superconductors, can be discussed in terms of Majorana fermion zero modes. If the non-Abelian vortices hosting these zero modes form a regular triangular lattice – a natural situation for an Abrikosov lattice in a superconductor or a Wigner crystal in the context of quantum Hall liquids – the corresponding model of Majorana fermions hopping on a triangular lattice becomes particularly tractable. In terms of symmetry classification, such a Majorana model is in class D and allows for three types of ground states – a trivial insulator, a Chern insulator and a thermal metal state. While the Chern insulator is found for uniform hopping [1], sufficiently strong sign-disorder in the hopping amplitudes will drive the system into the thermal metal state [2].

Here we investigate the stability of this thermal metal state when introducing an additional level of disorder – random bond or site depletion of the underlying triangular lattice. In particular, we are interested in addressing whether the thermal metal state is stable up to the respective percolation threshold of site/bond disorder.

First results will be discussed on this poster.

[1] E. Grosfeld and A. Stern, Phys. Rev. B 73, 201303(R) (2006).

[2] C. R. Laumann et al., Phys. Rev. B 85, 161301(R) (2012).