Abstract

The surprising discovery of superconductivity in MgB₂¹ at remarkably high transition-temperahires challenges the limits of phonon-mediated superconductivity, a fundamental question in view of suggested phonon involvement in the high-T_c cuprates. Possible anisotropic or unconventional pairing mechanisms have inspired experiments which probe the density of states and superconducting gap, but the large variation of gap values from surface-sensitive and bulk probes seems puzzling.²

© 2002 Optical Society of America