Flicker and random telegraph noise between gyrotropic and dynamic C-state of a vortex based spin torque nano oscillator

• Published in: AIP Advances Vol. 11; no. 3; pp. 035042 - 035042-5
• Main Authors: Wittrock, Steffen, Talatchian, Philippe, Romera, Miguel, Garcia, Mafalda Jotta, Cyrille, Marie-Claire, Ferreira, Ricardo, Lebrun, Romain, Bortolotti, Paolo, Ebels, Ursula, Grollier, Julie, Cros, Vincent
• Format: Journal Article Publication
• Language: English
• Published: Melville American Institute of Physics 01-03-2021; American Institute of Physics- AIP Publishing LLC; AIP Publishing LLC
• Subjects: Flicker; Noise; Noise prediction; Optimization; Oscillators; Physics; Spin dynamics; Torque; Vortices; Spintorque oscillator; Noise Measurement; Spintronic device
• ISSN: 2158-3226; 2158-3226
• DOI: 10.1063/9.0000197

Vortex based spin torque nano oscillators (STVOs) can present more complex dynamics than the spin torque induced gyrotropic (G) motion of the vortex core. The respective dynamic modes and the transition between them can be controlled by experimental parameters such as the applied dc current. An interesting behavior is the stochastic transition from the G-to a dynamic C-state occurring for large current densities. Moreover, the C-state oscillations exhibit a constant active magnetic volume. We present noise measurements in the different dynamic states that allow accessing specific properties of the stochastic transition, such as the characteristic state transition frequency. Furthermore, we confirm, as theoretically predicted, an increase of flicker noise with Idc2 when the oscillation volume remains constant with the current. These results bring insight into the potential optimization of noise properties sought for many potential rf applications with spin torque oscillators. Furthermore, the investigated stochastic characteristics open up new potentialities, for instance in the emerging field of neuromorphic computing schemes.