Microgmagnetics Study of Seed Induced Incoherent Magnetic Reversal in a Cobalt Element Array

A stochastic dynamic micromagnetics code using the LLG equation has been developed and applied to study the seed induced magnetic reversal of a cobalt element array. The spin orientation of the seed element is chosen to be antiparallel to the spin orientation of the first element in the array producing a domain wall that is stabilized by the strong crystalline anisotropy and exchange interactions of cobalt. By exposing the element array to an applied magnetic field for a specific time, the domain wall moved along the easy axis and was pinned at a specific position. In this manner, the portions of the element array to be switched could be controlled arbitrarily and information can be stored in the array in terms of the total magnetization of the array. The effects of the magnitude of applied field, the cutting area and the cellsize of the element array were also studied

Microgmagnetics Study of Seed Induced Incoherent Magnetic Reversal in a Cobalt Element Array

A stochastic dynamic micromagnetics code using the LLG equation has been developed and applied to study the seed induced magnetic reversal of a cobalt element array. The spin orientation of the seed element is chosen to be antiparallel to the spin orientation of the first element in the array producing a domain wall that is stabilized by the strong crystalline anisotropy and exchange interactions of cobalt. By exposing the element array to an applied magnetic field for a specific time, the domain wall moved along the easy axis and was pinned at a specific position. In this manner, the portions of the element array to be switched could be controlled arbitrarily and information can be stored in the array in terms of the total magnetization of the array. The effects of the magnitude of applied field, the cutting area and the cellsize of the element array were also studied

Magnetic Storage Device Using Induced Magnetic Reversal of a Cobalt Element Array

The effects of the applied field, cell size, and cutting area on the ‘‘seed’’ induced magnetic reversal of a cobalt element array have been studied by a stochastic dynamic micromagnetics code using the Laudau–Lifshitz–Gilbert equation. Three magnetic reversal mechanisms under different magnitudes of the applied field have been investigated by examining the energy profiles. To minimize the effect of the thermal fluctuations on the switching time, an applied field with magnitude around 0.7 or 0.8 T and an element array with cutting area less than 10 nm X 10 nm are required. By using the smaller cellsize, the switching time and the storage density of the element array can be improved. A sinusoidal applied field with a period of 0.1 ns was used to generate a single switching event

Monte Carlo Simulation on the Indirect Exchange Interactions of Co-doped ZnO Film

Monte Carlo simulations using a three-dimensional lattice model studied the Ruderman–Kittel–Kasuya–Yosida (RKKY) indirect exchange interaction of doped magnetic Co ions in ZnOfilms. The results of the calculations show that the RKKY interaction in Co-doped ZnO is long ranged and its magnitude is proportional to (inverse of the distance from a central ion). The sign oscillates with a frequency that depends on the concentration of the carrier. The long-distance sum of the RKKY indirect exchange energies is positive indicating that these materials are ferromagnetic, in direct correlation with previously reported results

Multispecies Coevolution Particle Swarm Optimization Based on Previous Search History

A hybrid coevolution particle swarm optimization algorithm with dynamic multispecies strategy based on K-means clustering and nonrevisit strategy based on Binary Space Partitioning fitness tree (called MCPSO-PSH) is proposed. Previous search history memorized into the Binary Space Partitioning fitness tree can effectively restrain the individuals’ revisit phenomenon. The whole population is partitioned into several subspecies and cooperative coevolution is realized by an information communication mechanism between subspecies, which can enhance the global search ability of particles and avoid premature convergence to local optimum. To demonstrate the power of the method, comparisons between the proposed algorithm and state-of-the-art algorithms are grouped into two categories: 10 basic benchmark functions (10-dimensional and 30-dimensional), 10 CEC2005 benchmark functions (30-dimensional), and a real-world problem (multilevel image segmentation problems). Experimental results show that MCPSO-PSH displays a competitive performance compared to the other swarm-based or evolutionary algorithms in terms of solution accuracy and statistical tests