ESR evidence for disordered magnetic phase from ultra-small carbon nanotubes embedded in zeolite nanochannels

TL;DR

This study uses multi-frequency ESR to reveal disordered magnetic phases, including ferromagnetic and spin-glass behavior, in ultra-small carbon nanotubes embedded in zeolite channels, highlighting localized states without conduction ESR signals.

Contribution

It provides the first ESR evidence of disordered magnetic phases in ultra-small carbon nanotubes confined in zeolite nanochannels, emphasizing localized states and magnetic behavior.

Findings

Evidence of low-temperature ferromagnetic/spin-glass behavior

Absence of conduction ESR signals

Localized states with high density (~3 x 10^19 /g)

Abstract

A multi-frequency electron spin resonance (ESR) study provides evidence for the occurrence of low temperature ferromagnetic/spin-glass behavior in aligned arrays of sub-nanometer single walled carbon nanotubes confined in zeolite nano-channels, owing to sp2-type non-bonding carbon associated localized states with density of ~3 x 1019 /g. Features related to the much anticipated conduction ESR are not detected. In the paramagnetic phase, the ESR linewidth is found to be weakly dependent on microwave frequency.