Momentum dependence of the superconducting gap and in-gap states in MgB2 multiband superconductor

Abstract

We use tunable laser-based angle-resolved photoemission spectroscopy to study the electronic structure of the multiband superconductor MgB2. These results form the baseline for detailed studies of superconductivity in multiband systems. We find that the magnitude of the superconducting gap on both σ bands follows a BCS-like variation with temperature with Δ0∼7meV. The value of the gap is isotropic within experimental uncertainty and in agreement with a pure s-wave pairing symmetry. We also observe in-gap states confined to kF of the σ band that occur at some locations of the sample surface. The energy of this excitation, ∼3 meV, is somewhat larger than the previously reported gap on π Fermi sheet and therefore we cannot exclude the possibility of interband scattering as its origin.

Source-reported materials — not catalogue approval

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