Energy barriers for bit-encoding states based on 360° domain walls in ultrathin ferromagnetic nanorings

A numerical thermal stability study of the bit-encoding states in a proposed multi-level magnetic storage element based on an ultrathin ferromagnetic nanoring is presented. The material parameters and the ring dimensions for which there are five distinct metastable magnetization configurations separated by energy barriers exceeding 50k_BT at room temperature are identified. The results are obtained, using the string method for the study of rare events to locate the transition states separating the metastable states and to identify the most likely thermally activated pathways.