English

Eavesdropping on competing condensates by the edge supercurrent in a Weyl superconductor

Superconductivity 2023-06-08 v3 Quantum Physics

Abstract

In a topological insulator the metallic surface states are easily distinguished from the insulating bulk states (FuKane07). By contrast, in a topological superconductor (FuKane08,Qi,FuBerg,Oppen), much less is known about the relationship between an edge supercurrent and the bulk pair condensate. Can we force their pairing symmetries to be incompatible? In the superconducting state of the Weyl semimetal MoTe2_2, an edge supercurrent is observed as oscillations in the current-voltage (\emph{I-V}) curves induced by fluxoid quantization (Wang). We have found that the ss-wave pairing potential of supercurrent injected from niobium contacts is incompatible with the intrinsic pair condensate in MoTe2_2. The incompatibility leads to strong stochasticity in the switching current IcI_c as well as other anomalous properties such as an unusual antihysteretic behavior of the ``wrong'' sign. Under supercurrent injection, the fluxoid-induced edge oscillations survive to much higher magnetic fields \emph{H}. Interestingly, the oscillations are either very noisy or noise-free depending on the pair potential that ends up dictating the edge pairing. Using the phase noise as a sensitive probe that eavesdrops on the competiting bulk states, we uncover an underlying blockade mechanism whereby the intrinsic condensate can pre-emptively block proximitization by the Nb pair potential depending on the history.

Keywords

Cite

@article{arxiv.2208.00933,
  title  = {Eavesdropping on competing condensates by the edge supercurrent in a Weyl superconductor},
  author = {Stephan Kim and Shiming Lei and Leslie M. Schoop and R. J. Cava and N. P. Ong},
  journal= {arXiv preprint arXiv:2208.00933},
  year   = {2023}
}

Comments

11 pages, 6 figures