2021/05/02 by Manish Anand · 5 citations
Engineering · Physics and Astronomy · #Anisotropy #Characterization and Applications of Magnetic Nanoparticles #Condensed matter physics #Dipole #Exchange interaction #Ferromagnetism #Magnetic anisotropy #Magnetic dipole–dipole interaction #Magnetic field #Magnetic nanoparticles #Magnetic properties of thin films #Magnetization #Materials science #Nanoparticle #Nanotechnology #Nuclear magnetic resonance #Optics #Physics #Relaxation (psychology) #Theoretical and Computational Physics #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1016/j.jmmm.2022.169201
published in Journal of Magnetism and Magnetic Materials 552, 169201 (Elsevier BV) · 25 pages,10 figures
arxiv created 2021/05/02 · openalex created_date 2021/05/10 · openalex publication_date 2022/03/01 · arxiv updated 2022/03/23 · openalex updated_date 2026/08/05
Using the two-level approximation of the energy barrier, we perform extensive kinetic Monte Carlo simulations to probe the relaxation characteristics in a two-dimensional (Lx× Ly) array of magnetic nanoparticle as a function of dipolar interaction strength hd, aspect ratio Ar=Ly/Lx, and temperature T. In the case of weak dipolar interaction (hd≈0) and substantial temperature, the magnetic relaxation follows the Néel Brown model as expected. Interestingly, the dipolar interaction of enough strength is found to induce antiferromagnetic coupling in the square arrangement of MNPs (Ar=1.0), resulting in the fastening of magnetic relaxation with hd. There is also a rapid increase in relaxation even with Ar<100 above a particular dipolar interaction strength h⋆d, which gets enhanced with Ar. Remarkably, there is a slowing down of magnetic relaxation with hd for the highly anisotropic system such as linear chain of MNPs. It is because the dipolar interaction induces ferromagnetic interaction in such a case. The thermal fluctuations also affect the relaxation properties drastically. In the case of weak dipolar limit, magnetization relaxes rapidly with T because of enhancement in thermal fluctuations. The effect of dipolar interaction and aspect ratio on the magnetic relaxation is also clearly indicated in the variation of Néel relaxation time τN. In the presence of strong dipolar interaction (hd>0.3) and Ar=1.0, τN decreases with hd for a given temperature. On the other hand, there is an increase in τN with hd for huge Ar (>100). We believe that the concepts presented in this work are beneficial for the efficient use of self-assembled MNPs array in data storage and other related applications.