de Haas-van Alphen effect in single crystal MgB₂

Observations of quantum oscillations in single crystals of the high temperature superconductor MgB₂ were reported. Three dHvA frequencies were resolved to two distinct orthogonal Fermi surfaces parallel to the main symmetry axes of MgB₂. Comparison with band structure suggested that the electron-phonon enhancement was large for the c-axis tube and much smaller for the in-plane electron-like tube. It was found from the comparisions of the band structures, that the electron-phonon coupling strength was a fctor of ∼3 larger for the c-axis tube orbits than for the in-plane network orbit.