Probing the atomic-scale dynamics of correlated systems using in-plane Current-Tuned Scanning Tunneling Microscopy and Spectroscopy (CT-STM/STS)

The charge density wave (CDW) is a symmetry-broken phase that emerges in many low-dimensional quantum materials due to electronic/lattice instabilities. While the macroscopic dynamic properties of the CDW have been studied in transport and x-ray measurements, evidence of atomic-scale dynamics such as CDW sliding and pinning still remain elusive. To address this challenge, we have integrated multiple electrical contacts into our scanning tunneling microscope (STM) in order to drive in-plane electrical current through a crystal while simultaneously performing electronic transport and local topography/scanning tunneling spectroscopic (STS) measurements.

In this talk, we will demonstrate the capabilities of in-plane Current Tuned-STM/STS (CT-STM/STS) to characterize CDW dynamics in a prototypical quasi-one-dimensional material, potassium blue bronze (K_0.3MoO₃). Interestingly, we find that in-plane electronic transport can have a dramatic effect on the surface STM/STS measurements. In particular, by analyzing topographic maps of the surface, we find that the spatial amplitude and phase of the CDW can be strongly dependent on in-plane driving current while CT-STS measurements as a function of in-plane current show hysteresis in the local density of states (LDOS). This study provides a clear example of how CT-STM/STS can be used to study the atomic-scale dynamics of correlated systems.