Fragility of surface states in topological superfluid <sup>3</sup>He.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33692358.
- Also identified by DOI 10.1038/s41467-021-21831-y and PMC identifier 7946958.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Superfluid <sup>3</sup>He, with unconventional spin-triplet p-wave pairing, provides a model system for topological superconductors, which have attracted significant interest through potential applications in topologically protected quantum computing. In topological insulators and quantum Hall systems, the surface/edge states, arising from bulk-surface correspondence and the momentum space topology of the band structure, are robust. Here we demonstrate that in topological superfluids and superconductors the surface Andreev bound states, which depend on the momentum space topology of the emergent order parameter, are fragile with respect to the details of surface scattering. We confine superfluid <sup>3</sup>He within a cavity of height D comparable to the Cooper pair diameter ξ<sub>0</sub>. We precisely determine the superfluid transition temperature T<sub>c</sub> and the suppression of the superfluid energy gap, for different scattering conditions tuned in situ, and compare to the predictions of quasiclassical theory. We discover that surface magnetic scattering leads to unexpectedly large suppression of T<sub>c</sub>, corresponding to an increased density of low energy bound states.