Magnetic tunneling with CNT-based metamaterial

0503954 - GLÚ 2020 RIV GB eng J - Journal Article
Kletetschka, Günther - Inoue, J. - Lindauer, J. - Hůlka, Z.
Magnetic tunneling with CNT-based metamaterial.
Scientific Reports. Roč. 9, č. 1 (2019), č. článku 2551. ISSN 2045-2322. E-ISSN 2045-2322
Institutional support: RVO:67985831
Keywords : carbon nanotubes * remanent magnetization * magnetic property * magnetite
OECD category: Geology
Impact factor: 3.998, year: 2019
Method of publishing: Open access
https://www.nature.com/articles/s41598-019-39325-9

Multiwall carbon nanotubes (MWCNTs) fabricated by chemical vapor deposition contain magnetic nanoparticles. While increasing frequency of electromagnetic field (EMF) exposure (up to <10 kHz) of MWCNTs resulted in slight induced magnetization decrease due to skin effect of the conducting carbon, we discovered that higher frequencies (>10 kHz) contained an exponential magnetization increase. We show that puzzling magnetization increase with decreasing magnetic field amplitude (less than 0.5 A/m for 512 kHz) is due to matching the field amplitudes of the magnetic nanoparticles inside nanotubes. This observation reveals a possibility of magnetic tunneling in MWCNTs (change of magnetic state of blocked magnetic moments). This interpretation is supported by observation of unblocking larger magnetic remanence (MR) portion from MWCNTs with progressively smaller amplitude of oscillating magnetic field.
Permanent Link: http://hdl.handle.net/11104/0295709