Magnetic ordering in arrays of one-dimensional nanoparticle chains

• Published in: Journal of physics. D, Applied physics Vol. 42; no. 21; pp. 215003 - 215003 (9)
• Main Authors: Serantes, D, Baldomir, D, Pereiro, M, Hernando, B, Prida, V M, Sánchez Llamazares, J L, Zhukov, A, Ilyn, M, González, J
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 07.11.2009; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic properties and materials; Magnetic properties of nanostructures; Physics; Mean field approximation; Magnetization; Magnetic ordering; Ferromagnetic materials; Magnetic moments; Microscopic model; Dipole interactions; Nanoparticles; Monte Carlo methods; Magnetic particles; Particle interactions; Magnetic anisotropy; One-dimensional systems
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/42/21/215003

The magnetic order in parallel-aligned one-dimensional (1D) chains of magnetic nanoparticles is studied using a Monte Carlo technique. If the easy anisotropy axes are collinear along the chains a macroscopic mean-field approach indicates antiferromagnetic (AFM) order even when no interparticle interactions are taken into account, which evidences that a mean-field treatment is inadequate for the study of the magnetic order in these highly anisotropic systems. From the direct microscopic analysis of the evolution of the magnetic moments, we observe spontaneous intra-chain ferromagnetic (FM)-type and inter-chain AFM-type ordering at low temperatures (although not completely regular) for the easy-axes collinear case, whereas a random distribution of the anisotropy axes leads to a sort of intra-chain AFM arrangement with no inter-chain regular order. When the magnetic anisotropy is neglected a perfectly regular intra-chain FM-like order is attained. Therefore it is shown that the magnetic anisotropy, and particularly the spatial distribution of the easy axes, is a key parameter governing the magnetic ordering type of 1D-nanoparticle chains.