Joint European Magnetic Symposia

Interacting magnetic nanoobjects constitute one key component for many proposed spintronic devices, from microwave nanooscillators to magnetic memory elements. For this reason, the mechanism of this interaction and its dependence with distance d between nanoobjects has been the subject of several recent studies [1]. In the present work, through micromagnetic simulation, we have investigated interacting pairs of nanodisks presenting magnetic vortex structure, in the form of an area array of fifty 20 nm-thick disk pairs. The disk diameters follow a Gaussian distribution centered at 250 nm and standard deviation that can be varied. In order to verify the magnetic coupling strength as a function of the distance between the disks of each pair, we have used a recently developed tool, the magnetic vortex echoes. This is an effect analogous to the NMR spin echoes, and arises from the gyrotropic motion of the vortex cores in arrays of inhomogeneous disks [2]. Analyzing the vortex echo, in quite similar way as done for NMR, it is possible to obtain two relaxation times, T2 and T2*, which depend on the interactions between the nanodisks, diameter distribution and Gilbert damping constant. T2* is directly related to the interaction strength [2] We determined the dependence of this strength with d, for the 50 disk pairs array, as also found in studies employing other techniques [1, 3]. [1] H. Jung, et al. Sci. Rep. 59, 1-6 (2011/08/10/online). [2] ArXiv:1201.3553. [3] O.V. Sukhostavets, J.M. Gonzalez and K.Y. Guslienko, Appl. Phys. Express 4, 065003 (2011).