A Direct Probe of Electronic Nematic Order; Symmetry Information in Scanning Tunneling Microscope Images

TL;DR

This paper proposes using Fourier-transformed local density of states patterns from STM images as a direct method to detect electronic nematic order and its symmetry breaking in materials, especially near phase transitions.

Contribution

It introduces a novel approach to identify nematic order through LDOS patterns and their Fourier transforms, providing a clear symmetry signature in STM data.

Findings

LDOS patterns reveal nematic symmetry breaking

Fourier-transformed LDOS can distinguish isotropic and nematic phases

Application to Sr3Ru2O7 demonstrates method's effectiveness

Abstract

An electronic nematic state spontaneously breaks a point-group symmetry of an underlying lattice. As a result, the nematic-isotropic transition accompanies a Fermi surface distortion. However, the anisotropic nature of the nematic state at a macroscopic scale can be easily wiped out when domains of different orientations of nematic order exist. We suggest that a spatial pattern of local density of states (LDOS) in the presence of a non-magnetic impurity can be a direct probe of the nematic order. We study various patterns of LDOS across the quantum phase transition between the isotropic and nematic phases. Especially the Fourier transformed local density of states (FT-LDOS), which can be deduced from scanning tunneling microscope images, represent a transparent symmetry of an electronic structure. The application of our results to the bilayer ruthenate, Sr$_3$Ru$_2$O$_7$ is also discussed.