Fermi Surface Sheet-Dependent Superconductivity in 2 H -NbSe 2

Abstract

High-resolution angle-resolved photoemission spectroscopy was used to study the superconducting energy gap and changes in the spectral function across the superconducting transition in the quasi–two-dimensional superconductor 2 H -NbSe 2 . The momentum dependence of the superconducting gap was determined on different Fermi surface sheets. The results indicate Fermi surface sheet–dependent superconductivity in this low–transition temperature multiband system and provide a description consistent with thermodynamic measurements and the anomalous de Haas–van Alphen oscillations observed in the superconducting phase. The present data suggest the importance of Fermi surface sheet–dependent superconductivity in explaining exotic superconductivity in other multiband systems with complex Fermi surface topology, such as the borides and f-electron superconductors.