Magnetic Study Of Single Domain Construction Particle System

The single-domain structure is the most basic element in magnetic materials,and it is important that understanding its magnetizing behavior under DC and AC fields for understanding single domain particle systems.We derive the hysteresis loop(static magnetism)of single domain uniaxial anisotropic particles based on the Stoner-Wohlfarth(SW)model,and study the effect of dipolar interaction on the static and dynamic magnetism of SW particle system.Finally,we also study the improvement of the resonance frequency of SW particle system in the stripe structure,and also found spin wave in this system.1.The anti-trigonometric function is used to strictly solve the uniaxial anisotropic Stoner-Wohlfarth(SW)model,which can obtain the relation of the angle()between the magnetization(the anisotropy field)and the applied magnetic field.Using this analytic solution,the hysteresis loops of uniaxial anisotropic SW particles magnetized in typical directions could be numerically calculated.Then,the hysteresis loops are obtained in randomly distributed SW particle ensembles while ignoring the dipole interaction among them with the analytic solution.Finally,the correctness of the analytic solution is verified by the exact solutions of remanence,switching field,and coercivity from SW model.2.The dipole-dipole interaction in the in-plane uniaxial magnetic anisotropy Co₉₃Zr₇array films are studied.The dipolar energy and dipolar field in Co₉₃Zr₇arrays are calculated,and the equation of resonance frequency with considering dipolar interaction is also obtained.The theoretical predictions and experimental results are consistent,both of which show the resonance frequency of arrays increase as the dipolar interaction increases.The magnetic properties of the arrays are determined by the competition between dipolar interaction and uniaxial anisotropy.when the critical ratio of the dipolar field to the uniaxial anisotropic field is less 50%,the distribution of magnetic moments is stable.3.The spin waves of single domain in-plane anisotropic strip array films are studied.The in-plane isotropic Fe50Co50 alloy thin films are grow on Si(111)substrates by magnetron sputtering,then the continuous Fe50Co50 thin films are etched into strip pattern films to induce the maximum2000 Oe in-plane shape anisotropy field,thereby increasing the resonant frequency of Fe50Co50 film to above 18 GHz.At the same time,we also observed the spin standing waves in this high in-plane uniaxial magnetic anisotropy Fe50Co50 material,and the larger the in-plane anisotropy field,the easier it is to generate spin waves.The frequency of spin standing waves can reach up to 25 GHz or more.