Thermal Stability of Magnetic States in Circular Thin-Film Nanomagnets with Large Perpendicular Magnetic Anisotropy

Abstract

Nanoscale ferromagnetic structures are of great interest for magnetic random-access memory (MRAM), but how stable are their bits? The authors investigate how the energy barrier to unwanted thermally induced transitions scales with size, in thin disks with large perpendicular magnetic anisotropy. They predict a critical diameter above which the barrier depends not on the disk's volume, but on its width. Their analytical model is easily applied to interpreting experiments and guiding design, to ensure that stored data will last.