Giant Raman Intensity Modulation in Pristine Carbon Nanotubes

TL;DR

This study reports significant modulation of Raman intensity in pristine quasi-metallic carbon nanotubes due to gate potentials, linked to electronic properties, with no change in resonance conditions, highlighting a potential connection to Mott insulating behavior.

Contribution

It reveals a large gate-induced Raman intensity modulation in pristine quasi-metallic carbon nanotubes, suggesting a link to electronic correlations like Mott insulating states.

Findings

Raman intensity varies by up to two orders of magnitude with gate voltage.

No change in resonance condition across the intensity variation.

Effect observed only in quasi-metallic, not semiconducting nanotubes.

Abstract

Large variations of up to two orders of magnitude are observed in the Raman intensity of pristine, suspended quasi-metallic single-walled carbon nanotubes in response to applied gate potentials. No change in the resonance condition is observed, and all Raman bands exhibit the same changes in intensity, regardless of phonon energy or laser excitation energy. The effect is not observed in semiconducting nanotubes. The electronic energy gaps correlate with the drop in the Raman intensity, and the recently observed Mott insulating behavior is suggested as a possible explanation for this effect.