Extended van Hove singularity, strong electron–phonon interaction and superconducting gap in doped Bi-2212 single crystals

Tunneling spectroscopy studies of high-temperature superconductors (HTSC) are overviewed. Facts are presented evidencing the strong electron–phonon interaction and the scaling of a superconducting gap and a critical temperature in doped Bi-2212 single crystals. A sharp extra structure in the current-voltage characteristics (CVC's) of Bi-2212 contacts is attributed to the presence of the extended van Hove singularity (EVHS) close to the Fermi level in slightly overdoped and slightly underdoped samples. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)