Minimal switching voltage for magnetization reversals in asymmetric nanorings

Micromagnetic simulations based on the Landau-Lifshitz-Gilbert equation are presented to study spin-polarized current induced magnetization switching in a symmetric nanoring-shaped magnetic tunnel junctions. The results show that in an a noring with an intermediate eccentric distance S, the critical switching voltage V(C) reaches the minimum whose magnitude is less than half of the voltage for a symmetric nanoring. In addition to the spin-transfer torque, the current induced Ampere ere. field is found to play a crucial part in the switching process. Analysis is given to explain the existence of such an energy valley that leads to the minimal voltage. (C) 2009 Elsevier B.V. All rights reserved.