Thermally Excited Mag-Noise in Ferromagnetic Ring Structures

As the dimension of magnetic devices drastically decreases to nanometer range, thermally excited mag-noise gradually becomes the dominant noise source. Thermally excited mag-noise plays an important role in ferromagnetic ring structures. By conducting micromagnetic simulation, the saturated state, triangle state, half triangle state, onion state, and vortex state are explored and studied, respectively. The mag-noise calculation shows that triangle state is the main reason for the mag-noise exhibiting 1/f tendency in both the low-frequency range and high-frequency range in relaxed state, while the onion state explains why a noise peak appears in high-frequency range in relaxed state. Meanwhile, it is proved that the area of the ferromagnetic rings is not the determining factor for the mag-noise distribution in saturated state. These results offer the theoretical framework for explaining the relation between domain structure and mag-noise, which is conducive to the future application of ferromagnetic ring structures as magnetic random access memory elements.