حسین رعنایی

In this research, the influence of the defect in magnetic properties of magnetic Permalloy nanodots has been investigated by using micromagnetic simulations. It has been shown that the magnetic reversal depends on both defect shapes and their positions in the dots. This influences the creation, pinning, depinning and annihilation of the vortex state. The nucleation field decreases with circular defects as compared to the other defects. Both coercivity and nucleation field varied significantly when triangle and circular defects get closer to the dot boundaries. However, by increasing the number of the defects, the coercivity is increased. The relative distances and arrangements of defects also affect the magnetic properties. The creation of vortex state and the perdurability of this state can be understood by considering the competition between demagnetization and exchange energy which is realized in simulated demagnetization energy.