Dispersion of Ordered Stripe Phases in the Cuprates

TL;DR

This paper presents a phase separation model for stripe phases in cuprates, explaining doping-dependent photoemission spectra and linking spectral features to stripe order and fluctuations.

Contribution

It introduces a theoretical model analyzing well-ordered stripe arrays, including Coulomb effects, and connects spectral features to experimental observations in cuprates.

Findings

Dispersion can be viewed as a superposition of end-phase dispersions.

Largest minigap occurs near the Fermi level and can be enhanced by Van Hove singularities.

Spectral features correlate with experimental photoemission data and stripe fluctuations.

Abstract

A phase separation model is presented for the stripe phase of the cuprates, which allows the doping dependence of the photoemission spectra to be calculated. The idealized limit of a well-ordered array of magnetic and charged stripes is analyzed, including effects of long-range Coulomb repulsion. Remarkably, down to the limit of two-cell wide stripes, the dispersion can be interpreted as essentially a superposition of the two end-phase dispersions, with superposed minigaps associated with the lattice periodicity. The largest minigap falls near the Fermi level; it can be enhanced by proximity to a (bulk) Van Hove singularity. The calculated spectra are dominated by two features -- this charge stripe minigap plus the magnetic stripe Hubbard gap. There is a strong correlation between these two features and the experimental photoemission results of a two-peak dispersion in La$_{2-x}$Sr$_x$CuO$_4$, and the peak-dip-hump spectra in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. The differences are suggestive of the role of increasing stripe fluctuations. The 1/8 anomaly is associated with a quantum critical point, here expressed as a percolation-like crossover. A model is proposed for the limiting minority magnetic phase as an isolated two-leg ladder.