944 research outputs found
Theory of the leading edge gap in underdoped cuprates
We present the theory of the leading edge gap in the normal state of
underdoped high- materials. The consideration is based on a magnetic
scenario for cuprates. We show that as doping decreases, the increasing
interaction with paramagnons gives rise to a near destruction of the Fermi
liquid and this in turn yields precursors to wave pairing. We argue that
the leading edge gap at and a broad maximum in the spectral
function at are byproducts of the same physical phenomenon.Comment: 4 pages, revtex, two figure
Dispersion Anomalies in Cuprate Superconductors
We argue that the shape of the dispersion along the nodal and antinodal
directions in the cuprates can be understood as a consequence of the
interaction of the electrons with collective spin excitations. In the normal
state, the dispersion displays a crossover at an energy where the decay into
spin fluctuations becomes relevant. In the superconducting state, the antinodal
dispersion is strongly affected by the spin resonance and displays an S-shape
whose magnitude scales with the resonance intensity. For nodal fermions,
relevant spin excitations do not have resonance behavior, rather they are
better characterized as a gapped continuum. As a consequence, the S-shape
becomes a kink, and superconductivity does not affect the dispersion as
strongly. Finally, we note that optical phonons typically lead to a temperature
independent S-shape, in disagreement with the observed dispersion.Comment: 12 pages, 7 eps figure
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