Controlling local relaxation in small clusters of magnetic nanoparticles

We investigate the local (particle level) and averaged magnetic relaxation characteristics in linear chain-like agglomerates of k magnetic nanoparticles (MNPs) or k-mers using computer simulations. The local relaxation behaviour is dictated by the corresponding dipolar field acting on the nanoparticle, irrespective of k-mer size. There is a wide variation in local relaxation characteristics as a function of nanoparticle position in a small nanocluster. On the other hand, there is more uniformity in the local relaxation response with a larger kmer, except for MNPs at the boundary. Interestingly, there is a smooth decay of magnetization with small h(d), independent of cluster size. In contrast, the magnetization ceases to relax in the presence of substantial dipolar interaction strength. Remarkably, the local Neel relaxation time tau(')(N) is directly proportional to the corresponding dipolar field. Likewise, the averaged Neel relaxation time tau(N) also depends strongly on the k-mer size and h(d).

Automated summary

In linear chain-like agglomerates of magnetic nanoparticles, the local relaxation behavior is influenced by the dipolar field acting on the nanoparticles, which varies with nanoparticle position. A larger k-mer results in more uniform local relaxation response, except for the nanoparticles at the boundary. The smooth decay of magnetization is independent of cluster size, while magnetization ceases to relax in the presence of substantial dipolar interaction strength.