Strain-induced metal-semiconductor transition observed in atomic carbon chains

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Carbyne, the sp(1)-hybridized carbon allotrope, remains largely uncharacterized in bulk form.
• Linear chains of carbon atoms, the fundamental units of carbyne, have been observed via electron microscopy.
• These one-dimensional atomic chains are theoretically predicted to be novel conductors, but experimental data is scarce.

Purpose of the Study:

• To experimentally investigate the electrical properties of monoatomic carbon chains.
• To explore the influence of strain on the electronic behavior of these one-dimensional systems.
• To validate theoretical predictions regarding carbyne's electronic phase transitions.

Main Methods:

• Electrical transport measurements on isolated monoatomic carbon chains.
• First-principles density functional theory calculations for electronic structure and transport.
• Analysis of strain-induced changes in atomic structure and conductivity.

Main Results:

• Monoatomic carbon chains exhibit strain-dependent electrical properties.
• Under strain, chains transition to a semiconducting polyyne structure with alternating bond lengths.
• Unstrained chains display ohmic behavior characteristic of metallic cumulene with uniform bond lengths.
• A strain-induced metal-insulator transition was experimentally confirmed.
• Rectifying behavior was observed in non-symmetric contact configurations, highlighting the role of leads.

Conclusions:

• Monoatomic carbon chains can be tuned between metallic and semiconducting states via mechanical strain.
• This work provides crucial experimental validation for theoretical models of carbyne.
• The findings open avenues for novel electronic devices based on one-dimensional carbon structures.