Competing periodicities in fractionally filled one-dimensional bands

TL;DR

This study investigates the complex charge density wave transitions in the quasi-one-dimensional Si(553)-Au system, revealing competing periodicities and potential for manipulating phase solitons at atomic scales.

Contribution

It provides detailed experimental evidence of multiple CDW transitions and competing periodicities in a fractionally filled 1D band system, highlighting new insights into electronic instabilities.

Findings

Observation of multiple charge density wave transitions.

Identification of competing periodicities and charge transfer.

Potential to manipulate phase solitons with specific charge and spin properties.

Abstract

We present a variable temperature Scanning Tunneling Microscopy and Spectroscopy (STM and STS) study of the Si(553)-Au atomic chain reconstruction. This quasi one-dimensional (1D) system undergoes at least two charge density wave (CDW) transitions at low temperature, which can be attributed to electronic instabilities in the fractionally-filled 1D bands of the high-symmetry phase. Upon cooling, Si(553)-Au first undergoes a single-band Peierls distortion, resulting in period doubling along the imaged chains. This Peierls state is ultimately overcome by a competing tripleperiod CDW, which in turn is accompanied by a x2 periodicity in between the chains. These locked-in periodicities indicate small charge transfer between the nearly half-filled and quarter-filled 1D bands. The presence and the mobility of atomic scale dislocations in the x3 CDW state indicates the possibility of manipulating phase solitons carrying a (spin,charge) of (1/2,+-e/3) or (0,+-2e/3).