Noise Predictions for STM in Systems with Local Electron Nematic Order

TL;DR

This paper predicts that thermal fluctuations in stripe orientations caused by quenched disorder in electronic systems can be detected as telegraph noise in STM measurements, providing insights into local nematic order and disorder effects.

Contribution

It introduces a novel prediction that thermally excited stripe orientation fluctuations produce detectable noise in STM, linking disorder, nematic order, and thermal effects.

Findings

Thermal fluctuations cause telegraph noise in STM measurements.

Noise characteristics depend on temperature and spatial location.

Proposes an in-situ test to distinguish correlated from independent noise sources.

Abstract

We propose that thermal noise in local stripe orientation should be readily detectable via STM on systems in which local stripe orientations are strongly affected by quenched disorder. Stripes, a unidirectional, nanoscale modulation of electronic charge, are strongly affected by quenched disorder in two-dimensional and quasi-two-dimensional systems. While stripe orientations tend to lock to major lattice directions, dopant disorder locally breaks rotational symmetry. In a host crystal with otherwise $C_4$ rotational symmetry, stripe orientations in the presence of quenched disorder map to the random field Ising model. While the low temperature state of such a system is generally a stripe glass in two dimensional or strongly layered systems, as the temperature is raised, stripe orientational fluctuations become more prevalent. We propose that these thermally excited fluctuations should be readily detectable in scanning tunneling spectroscopy as {\em telegraph noise} in the high voltage part of the local $I(V)$ curves. We predict the spatial, temporal, and thermal evolution of such noise, including the circumstances under which such noise is most likely to be observed. In addition, we propose an in-situ test, amenable to any local scanning probe, for assessing whether such noise is due to correlated fluctuations rather than independent switchers.