THz phonon spectroscopy of doped superconducting cuprates
Ya. G. Ponomarev, H. H. Van, S. A. Kuzmichev, S. V. Kulbachinskii, M. G. Mikheev, M. V. Sudakova, S. N. Tchesnokov
Department of Low Temperature Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
Abstract
Facts are presented evidencing a strong electron-phonon
interaction in doped BSCCO superconductors. A pronounced fine structure in
dI/dV-characteristics of Josephson junctions has been observed which is
caused by interaction of АС Josephson current with Raman-active optical
phonon modes. "Quantization" of the "gap" voltage for natural nanosteps
on the cryogenically cleaved surfaces of BSCCO proves the existence of the
intrinsic Josephson effect. A sharp extra structure in the current-voltage
characteristics of nanosteps is attributed to the presence of the extended
van Hove singularity.