Reversal Mode of Thermally Assisted Magnetization Reversal on Perpendicularly Magnetized Nano-dot

Abstract

In these micro magnetic simulations, a finite-grid approximation was adopted, where a parallelepiped dot with perpendicular anisotropy was discretized into a two-dimensional array of a rectangular numerical grid. The grid size was chosen to be larger than the exchange length. The demagnetization fields are calculated by integrating those from apparent surface magnetic charges on boundary of each grid element. Thermally assisted magnetization reversal, where the switching field is temporally reduced by heating the selected memory cell in the writing process, is considered in this simulation. Switching mode of thermally assisted magnetization reversal has been numerically investigated by solved Landau-Lifshift Gilbert equation for magnetic nano-dot with perpendicular anisotropy. This thermally scheme succeed to decrease reversal field down to hundreds Oe order. An oscilatory minimum field required for aligning magnetization along writing field direction was observed which can be attributed by an exchange length. This information gives the possibility to r ealize the high density of Magnetic Random Access Memories with small r eversal field (up to hundreds Oer sted order) in the rea ding and writing process.