Fermi arcs carry superconductivity in PtBi₂ while the bulk remains normal

The Weyl semimetal PtBi₂ exhibits a surprising phenomenon: superconductivity confined to its Fermi arcs while the bulk material remains non-superconducting. Researchers at the Leibniz Institute for Solid State and Materials Research and the University of London have now demonstrated that this arises from interactions between electrons on these arcs and phonons within the material. They identified two competing mechanisms governing the strength of this superconductivity, influenced by how effectively the surface screens electrical charges. Recent photoelectron spectroscopy experiments confirm the presence of nodes within the superconducting gap of PtBi₂, suggesting that surface coatings could be used to manipulate the material’s superconducting properties. Angle-resolved photoemission spectroscopy experiments on PtBi₂ reveal nodes within its superconducting gap, indicating an unconventional superconducting state with i-wave pairing symmetry. These nodes belong to a manifold of Majorana modes located at the center of…