Visualizing atomic scale deformation and de-pinning of a charge density wave

The charge density wave (CDW) is a symmetry-broken state of matter that is ubiquitous across quantum materials. Its signature is a periodic modulation of electron charge and lattice ions. In quasi one-dimensional systems, an applied electric field can distort the CDW before it finally de-pins itself and moves collectively through the crystal. Notably, this process has never been imaged directly. In this talk, I will show experiments that combine in-plane drive currents with scanning tunneling microscopy and spectroscopy (STM/STS) to investigate the nanoscale field-response on the surface of a prototypical Peierls CDW material, K0.3MoO3. By tuning the in-plane drive current, we directly visualize a hysteretic (“memory”) response in the surface CDW as it plastically deforms before evolving between ordered/disordered states through the annihilation/generation of topological defects (vortices) in the phase of the CDW order parameter. Our results demonstrate that surface CDWs are manipulable with behavior similar to proposed microscopic models of bulk CDW dynamics.