The influence of dipolar interaction on magnetic properties in nanomagnets with different shapes

Abstract

With the Monte Carlo method, we investigate the magnetic properties of four nanomagnets of different shapes, i.e., the circular-shaped, the square-shaped, the elliptical, and the ringshaped nanomagnets. A systematic study of the effects of the dipolar interaction on the magnetic configurations is performed in these nanomagnets, and further the coercive field and the remanence as a function of dipolar interaction are analyzed. The results show that the magnetic configuration and thus the magnetization reversal process of nanomagnets are dependent strongly on the strength of dipolar interactions. For the case of small dipolar interaction, the magnetization reversal process is mainly dominated by spin rotation, while the reversal transforms to the vortex nucleation and propagation formations with increasing dipolar interaction. Moreover, if the dipolar interaction is neglected in the calculation of the total energy, no clear difference is found among hysteresis loops of four nanomagnets with same areas, but the inclusion of dipolar interaction can lead to different hysteresis loops for nanomagnets with same areas but different shapes. This indicates that the dipolar interaction is important for accounting for the shape effect of the magnetic properties in nanomagnets.

Effect of anisotropy on small magnetic clusters

“…In the present work we have applied the exact diagonalization method to calculate the properties of clusters with spin-1/2 and 1. We have studied the magnetic and thermodynamic properties of small clusters with the focus on showing the effect of dipolar interaction and uniaxial anisotropy on the magnetization behavior in the presence of magnetic field, the studies of which are still limited in literature [33][34][35] . In addition, the temperature-dependent as well as the ground state spin-spin correlation functions are calculated for these clusters and are compared with respect to the classical case.…”

Magnetization reversal in magnetic half-balls influenced by shape perturbations

“…Due to their potential applications, nanostructured ferromagnetic elements have been intensively studied over the past decade. 1,2 Such nanomagnets may improve efforts to continuative miniaturization of data storage media enabling higher data densities. 3,4 The dependence of magnetization reversal mechanisms on dimensions and shape of magnetic nanoparticles has been shown in several works for different shapes ͑e.g., ellipsoids and dots, 5 rectangles and triangles, 6 wires, 7 tubes, 8 and mixed geometries 9 ͒.…”

Directional-dependent coercivities and magnetization reversal mechanisms in fourfold ferromagnetic systems of varying sizes

“…18 Similar lateral sizes (50-300 nm) were often used in recent theoretical articles about magnetic nano-particles. 11,16,[19][20][21][22][23][24] The slightly smaller dimensions considered here additionally exhibit interesting effects which have to be taken into account when our findings are to be transferred to applied solutions. To enhance the possibility of comparison of the square system under investigation with nano-patterned rings, 11,12,[25][26][27] we have chosen an in-plane oriented sample instead of perpendicularly oriented ferromagnetic regions as used in today's hard disks.…”