Condensed-Matter Physics & Materials Science Seminar

"ARPES spectra of hole- and electron-doped high Tc superconductors"

Presented by Denis Sunko, Department of Physics, University of Zagreb, Croatia

Tuesday, January 31, 2006, 1:30 pm — Small seminar room, Bldg. 510

The physical mechanism responsible for the narrow low-energy ARPES
peak in superconducting optimally doped and weakly underdoped BSCCO
near the van Hove point will be proposed in detail. The pseudogap is
taken to be due to electron-paramagnon scattering. The narrow peak is
antiadiabatic: it consists of electrons which are so slow that the
scattering is not effective in suppressing their spectral strength.
The leading-edge scale of this peak determined by the chemical
potential, and is not due to any separate dynamical phenomenon below
the AF scale of ~1000 K. There appear two temperature regimes for the
pseudogap. The low-temperature one is relevant for experiment in
BSCCO, where the paramagnon band-edge is much higher than the
temperature. The high-temperature regime occurs when the band-edge is
lower than the temperature. It is characterized by hot spots when the
band-edge is finite, and develops a macroscopic antiferromagnetic
potential when it vanishes. I shall argue that it is relevant for the
electron-doped high-Tc compounds. In that case, the wide structures
seen dispersing across the Fermi energy in NCCO are incoherent
features of the same pseudogap mechanism responsible for the BSCCO
spectrum, but in the opposite physical regime.

Hosted by: Tonica Valla

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