Bulk Fermi surface and momentum density in heavily doped La$_{2-x}$Sr$_x$CuO$_4$ using high resolution Compton scattering and positron annihilation spectroscopies

TL;DR

This study uses high-resolution Compton scattering and positron annihilation spectroscopies to observe and analyze the bulk Fermi surface in heavily doped La$_{2-x}$Sr$_x$CuO$_4$, confirming Fermi-liquid behavior in the overdoped regime.

Contribution

It demonstrates the effectiveness of Compton scattering and 2D-ACAR in detecting Fermi surfaces and validates DFT predictions for overdoped cuprates.

Findings

Clear Fermi surface signature observed in Compton scattering

Quantitative agreement between DFT calculations and experiments

2D-ACAR spectra show less distinct Fermi surface signatures

Abstract

We have observed the bulk Fermi surface (FS) in an overdoped ($x$=0.3) single crystal of La$_{2-x}$Sr$_x$CuO$_4$ by using Compton scattering. A two-dimensional (2D) momentum density reconstruction from measured Compton profiles yields a clear FS signature in the third Brillouin zone along [100]. The quantitative agreement between density functional theory (DFT) calculations and momentum density experiment suggests that Fermi-liquid physics is restored in the overdoped regime. In particular the predicted FS topology is found to be in good accord with the corresponding experimental data. We find similar quantitative agreement between the measured 2D angular correlation of positron annihilation radiation (2D-ACAR) spectra and the DFT based computations. However, 2D-ACAR does not give such a clear signature of the FS in the extended momentum space in either the theory or the experiment.