Nodal quasiparticle dispersion in strongly correlated<i>d</i>-wave superconductors

Abstract

We analyze the effects of a $\mathbf{k}$-dependent self-energy on the photoemission momentum distribution curve (MDC) line shape and dispersion and, in particular, show that this modifies the ``high-energy'' dispersion ${v}_{F}^{\mathrm{high}}$ of the MDC's in an essential way. These general results are illustrated by a detailed examination of nodal quasiparticles in the superconducting state of the high-${T}_{c}$ cuprates. Using variational results for the nodal quasiparticle weight Z, which vanishes with the hole doping x, and the low energy dispersion ${v}_{F}^{\mathrm{low}},$ which is independent of x, we show that the ``high-energy'' dispersion ${v}_{F}^{\mathrm{high}}{=v}_{F}^{\mathrm{low}}/Z$ is much larger than the band structure value and exhibits a striking doping dependence in good agreement with recent data. These results provide strong evidence for an electronic origin of all the nodal dispersion anomalies, including the much-studied kink.