# Measurement of the Axial Magnetic Susceptibility of m-SWCNTs at High Temperatures in a Magnetic Field-Assisted FC-CVD

## TL;DR

The study measures the magnetic properties of m-SWCNTs at high temperatures and finds that defects significantly enhance their magnetic behavior.

## Contribution

This is the first measurement of axial magnetic susceptibility of m-SWCNTs, revealing a significant increase due to defects.

## Key findings

- The axial magnetic susceptibility of m-SWCNTs at 1273 K is two orders of magnitude higher than at 300 K.
- Defects in m-SWCNTs increase their Curie temperature and Curie constant.
- Spin-polarized density functional theory supports the observed magnetic behavior due to vacancies.

## Abstract

We synthesized some SWCNTs films under different magnetic fields and temperatures in a magnetic field-assisted FC-CVD and obtained Raman spectra of the films. By analyzing the Raman spectra, it was concluded that the SWCNTs films had defects, and the relative content of m-SWCNTs in the SWCNTs films was obtained. The trajectory of m-SWCNTs was obtained by analyzing the motion behavior of m-SWCNTs flow in the field-assisted system, and a model was built to describe the relationship between the relative content of m-SWCNTs and magnetic fields. The axial magnetic susceptibility of m-SWCNTs as a parameter was obtained by fitting the experimental results and the model. This is the first time that the axial magnetic susceptibility of m-SWCNTs has been obtained. The result obtained at 1273 K is at least two orders of magnitude greater than the magnetic susceptibilities and anisotropies of purified m-SWCNTs at 300 K, indicating that the defects increase the Curie temperature and Curie constant of m-SWCNTs. This is consistent with the spin-polarized density functional theory, which predicts that m-SWCNTs with vacancies have local magnetic moments around the vacancies and exhibit ferro- or ferrimagnetism.