Micromagnetic study of the effect of Dzyaloshinskii-Moriya interaction on magnetization reversal in magnetic nanodots of different shape

Abstract

Thorough understanding of magnetization reversal process in perpendicularly magnetized nanostructures of different shapes in the presence of anti-symmetric exchange interaction is crucial in designing energy efficient magnetic storage devices. Here, we investigate the effect of interfacial Dzyaloshinskii-Moriya interaction (IDMI) and in-plane bias field (µ0H) on the magnetization reversal mechanism in perpendicularly magnetized square, circular and triangular nanodot of side length (diameter) 128 nm and thickness 1 nm using micromagnetic simulation Mumax3. Our results indicate a monotonic reduction in the coercive field with increase in the strength of IDMI and the nucleation of the reversal is observed at the edge of the nanodot irrespective of the shape. Additionally, the application of bias field pins the nucleation centre at the far edge of the dots and further lowers the energy barrier for the magnetization reversal with the extent of lowering related to the symmetry of the shape. Detailed analysis of energy profile reveals that due to the lateral asymmetry of the triangular nanodot (large spin canting), the total energy value is smaller for it at small magnitude of D (≤2 mJ/m2) and µ0H (≤100 mT) thereby making it preferred for energy efficient magnetization reversal in comparison to other two shapes. However, at sufficiently large magnitude of D (>2 mJ/m2) and µ0H (>100 mT), due to the laterally symmetric sides of the square (small spin canting), remarkable reduction of the energy barrier for the magnetization reversal is noticed. These findings indicate that the effect of D and µ0H in lowering the energy barrier for the magnetization reversal is intricately related to the symmetry associated with the shape of the nanodots. We thus believe that these results provide useful insight into the role of the shape of the nanoelement in designing spintronics devices where energy efficient magnetization reversal is required.