On the Origin of the Checkerboard Pattern in Scanning Tunneling Microscopy Maps of Underdoped Cuprate Superconductors

TL;DR

This paper investigates the origin of the checkerboard pattern in STM maps of underdoped cuprates, attributing it to interference effects in tunneling paths rather than nematic order, with implications for understanding electronic structure.

Contribution

It proposes that interference between tunneling paths through apical ions causes the checkerboard pattern, challenging previous nematic-based explanations.

Findings

Interference effects explain the checkerboard pattern.

Asymmetry in differential conductance favors localization length differences.

Pattern depends on tunneling geometry, not nematic displacement.

Abstract

The checkerboard pattern in the differential conductance maps on underdoped cuprates appears when the STM is placed above the O-sites in the outermost CuO$_{\text{2}}$-plane. In this position the interference between tunneling paths through the apical ions above the neighboring Cu-sites leads to an asymmetric weighting of final states in the two antinodal regions of ${\boldsymbol{k}}$-space. The form of the asymmetry in the differential conductance spectra in the checkerboard pattern favors asymmetry in the localization length rather than a nematic displacement as the underlying origin.