New Anomaly in the Transverse Acoustic Impedance of Superfluid He 3 − B with a Wall Coated by Several Layers of He 4

What is it about?

Our transverse acoustic impedance (Z) measurements by changing the boundary condition of a wall from a diffusive scattering up to practically specular limit revealed the systematic dependence of the bound states on the surface boundary condition or the surface disorder. A growth of low-energy peak in Z was observed at higher specularity, which is the clear indication of surface linear dispersion called Majorana cone.

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Why is it important?

Superfluid 3He B-phase is categorized as a time-reversal invariant topological superfluid. Surface bound states form due to the bulk-edge correspondence and are predicted to be Majorana fermions satisfying the equivalence of the particle and anti-particle. A growth of low-energy peak in Z was observed on a higher specularity wall, which is the clear indication of the surface linear dispersion called Majorana cone on a clean surface. This is the first and only confrimation of Majorana cone in so far reported topological superfluids and superconductors.