A critical look at topological superconductors

by Philip Brydon (University of Maryland)

Wednesday 4 Feb 2015, 09:45 → 10:20 Europe/Stockholm

132:028 Nordita East

The discovery that gapped electronic systems can have nontrivial topology has revolutionized in condensed matter physics. Topological superconductivity is particularly interesting, due to the Majorana nature of the protected edge states, but also very rare. This has prompted many proposals on how to create topological superconductors, several of which have apparently been successful.

To establish the existence of a topological state, however, alternative nontopological physics needs to be excluded. In this talk I take a critical look at two famous claims: (i) topological superconductivity in the doped topological insulators [1], and (ii) the observation of Majorana modes in ferromagnetic wires on a superconductor [2].

In both cases, I argue that there are compelling reasons for scepticism, although a topological state cannot be ruled out.

[1] P. M. R. Brydon, S. Das Sarma, H.-Y. Hui, and J. D. Sau, Phys. Rev. B. 90, 184512 (2014) [arXiv]
[2] J. D. Sau and P. M. R. Brydon, arXiv:1501.03149