title: Resonant amplification of vortex-core oscillations by coherent magnetic-field pulses.
abstract: Vortex structures in soft magnetic nanodisks are highly attractive due to their scientific beauty and potential technological applications. Here, we experimentally demonstrated the resonant amplification of vortex oscillations by application of simple coherent field pulses tuned to optimal width and time intervals. In order to investigate vortex excitations on the sub-ns time scale, we employed state-of-the-art time-resolved full-field soft X-ray microscopy of 70 ps temporal and 25 nm lateral resolution. We found that, due to the resonant enhancement of the vortex gyration motion, the signal input power can be significantly reduced to ~ 1 Oe in field strength, while increasing signal gains, by increasing the number of the optimal field pulses. We identified the origin of this behavior as the forced resonant amplification of vortex gyration. This work represents an important milestone towards the potential implementation of vortex oscillations in future magnetic vortex devices.
authors: National Creative Research Initiative Center for Spin Dynamics and Spin-Wave Devices, Department of Materials Science and Engineering, Seoul National University, Seoul, South Korea.
authors: Young-Sang
authors: YS
authors: Yu
authors: Dong-Soo
authors: DS
authors: Han
authors: Myoung-Woo
authors: MW
authors: Yoo
authors: Ki-Suk
authors: KS
authors: Lee
authors: Youn-Seok
authors: YS
authors: Choi
authors: Hyunsung
authors: H
authors: Jung
authors: Jehyun
authors: J
authors: Lee
authors: Mi-Young
authors: MY
authors: Im
authors: Peter
authors: P
authors: Fischer
authors: Sang-Koog
authors: SK
authors: Kim