Interplay between exchange interaction and magnetic anisotropy for iron based nanoparticles in aligned carbon nanotube arrays

• Published in: Carbon (New York) Vol. 68; pp. 337 - 345
• Main Authors: Danilyuk, A.L., Prudnikava, A.L., Komissarov, I.V., Yanushkevich, K.I., Derory, A., Le Normand, F., Labunov, V.A., Prischepa, S.L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.03.2014; Elsevier
• Subjects: Alignment; Anisotropy; Arrays; Carbon nanotubes; Chemical Sciences; Chemistry; Colloidal state and disperse state; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Correlation analysis; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; General and physical chemistry; Iron; Magnetic anisotropy; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Material chemistry; Materials science; Mathematical models; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Physics; Nanoparticles; Carbon nanotubes; Iron; Transition elements; Magnetic anisotropy
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2013.11.010

In this work, we investigate magnetic properties of iron based nanoparticles (NP) intercalated into carbon nanotube (CNT) aligned arrays synthesized by injection chemical vapor deposition. We have analyzed the temperature (T) and the ferrocene concentration (CF) dependences of the macroscopic magnetic parameters. From these experiments a weaker interaction between magnetic moments of NP was obtained for low CF values. The random anisotropy model for the experimental data analysis was applied and micromagnetic parameters were evaluated. The law of the approach to magnetic saturation (LAS) was analyzed using the general expression with the correlation function C(r=x/Ra) of magnetic axes, Ra being the magnetic anisotropy correlation length. We obtained that, while for CF=0.5% C(r) is a step-like (C(r<10)=1, C(r>10)=0), for CF⩾1% C(r) decays rapidly on a short range, (2-3)Ra. Such extended correlations for CF=0.5% could be associated with the dominant role of the coherent anisotropy, which is caused by the influence of the alignment of CNT. When the aligned CNTs for CF=0.5% are destroyed into powder, the LAS is changed to H−1/2, which means the dominant role of the exchange mechanism.