Point-contact spectroscopy of MgB2 in high magnetic fields

The point-contact spectroscopy data reveal the existence of two distinct superconducting energy gaps in the Andreev reflection of quasiparticles between MgB2 and a copper counterelectrode. Above the gap energies reproducible nonlinearities are observed at the characteristic phonon energies of MgB2. The strength and position of the observed nonlinearities due to the electron–phonon interaction do not reveal any renormalization when the point contact undergoes the transition from the superconducting to the normal state. [Copyright &y& Elsevier]