Topological Solitons versus Non-Solitonic Phase Defects in Quasi-One-Dimensional Charge Density Wave

TL;DR

This study uses low-temperature STM to distinguish intrinsic solitons from other phase defects in a quasi-1D CDW system, revealing their electronic structure, coherence length, and interactions with extrinsic defects.

Contribution

It provides direct experimental evidence of intrinsic solitons in a quasi-1D CDW system and characterizes their electronic and interaction properties.

Findings

Intrinsic solitons have a coherence length of about 4 nm.

Solitons exhibit localized electronic states within the CDW gap.

Moving solitons interact uniquely with extrinsic defects.

Abstract

We investigated phase defects in a quasi-one-dimensional commensurate charge density wave (CDW) system, an In atomic wire array on Si(111), using low temperature scanning tunneling microscopy. The unique four-fold degeneracy of the CDW state leads to various phase defects, among which intrinsic solitons are clearly distinguished. The solitons exhibit a characteristic variation of the CDW amplitude with a coherence length of about 4 nm, as expected from the electronic structure, and a localized electronic state within the CDW gap. While most of the observed solitons are trapped by extrinsic defects, moving solitons are also identified and their novel interaction with extrinsic defects is disclosed.