Magnetic Behavior of the Arrays of Iron Cylindrical Nanostructures: Atomistic Spin Model Simulations

Abstract

Cylindrical ferromagnetic nanowires are of particular interest in nanomaterials science due to various manufacturing methods and a wide range of applications in nanotechnology, with special attention given to those with diameters less than the single domain limit. In the current study, the simulations of magnetic properties of isolated iron nanowires with a diameter of 5 nm and various aspect ratios, as well as two types of arrays of such nanowires (with hexagonal and square arrangement), were performed using atomistic spin model. In the case of a single nanowire, change of coercive field for different applied field directions with aspect ratio was discussed. It was shown that the evolution of the magnetization reversal mechanism from coherent rotation to domain wall propagation appears with increasing length of single nanowire. For the arrays of cylindrical nanostructures, it was revealed that different number of nearest neighbors for each nanostructure in square and hexagonal arrays have an influence on their magnetostatic interactions, which are the most significant for shortest interwire distances. The corresponding spin configurations during the remagnetization process showed the appearance of intermediate magnetization states (when a part of wires is magnetized parallel and part antiparallel to the field direction), connected with Barkhausen effect, which influence the observed hysteresis curves.

Preparation, properties and biomedical applications progress of 1D magnetic nanomaterials with iron

“…For example, the coercivity and remanence of NWs could reduce with increasing the NW diameter due to the different strengths of magneto-static interaction among NWs. [77,78] The diameter dependence of magnetic properties of iron oxide NWs is much different from those of Fe or FeNi NW arrays with 500-600 Oe of the coercivity, and their coercivity decreases with the diameter from 380 Oe of 120 nm diameter NW to 630 Oe of 200 nm diameter NW [79,80]. When magnetic field is applied parallel and perpendicular the wire axis, respectively, Fe 3 O 4 NW arrays of D = 50 nm are superparamagnetic, however, the three other NWs of D = 100, 150 200 nm have remanence magnetisation and their coercivity increases with the diameter of NW arrays from 10 Oe of 50 nm diameter NW to 370 Oe of 200 nm diameter NW [44].…”