Beyond the gyrotropic motion: Dynamic C-state in vortex spin torque oscillators

• Published in: Applied physics letters Vol. 118; no. 1
• Main Authors: Wittrock, Steffen, Talatchian, Philippe, Romera, Miguel, Menshawy, Samh, Jotta Garcia, Mafalda, Cyrille, Marie-Claire, Ferreira, Ricardo, Lebrun, Romain, Bortolotti, Paolo, Ebels, Ursula, Grollier, Julie, Cros, Vincent
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 04-01-2021
• Subjects: Applied physics; Magnetic disks; Optimal control; Oscillators; Physics; Spin dynamics; Stability; Stochastic processes; Torque
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0029083

In the present study, we investigate a dynamical mode beyond the gyrotropic (G) motion of a magnetic vortex core in a confined magnetic disk of a nano-pillar spin torque nano-oscillator (STNO). It is characterized by the in-plane circular precession associated with a C-shaped magnetization distribution. We show a transition between G- and C-state modes, which is found to be stochastic in a current-controllable range. Supporting our experimental findings with micromagnetic simulations, we believe that the results provide further opportunities for the dynamic and stochastic control of STNOs, which could be interesting to be implemented, for example, in neuromorphic networks.