Decoherence and mode-hopping in a magnetic tunnel junction-based spin-torque oscillator

Abstract

We discuss the coherence of magnetic oscillations in a magnetic tunnel junction-based spin-torque oscillator as a function of external field angle. Time-frequency analysis shows mode-hopping between distinct oscillator modes, which arises from linear and nonlinear couplings in the Landau-Lifshitz-Gilbert equation, analogous to mode-hopping observed in semiconductor ring lasers. These couplings and therefore mode-hopping are minimized near the current threshold for antiparallel (AP) alignment of free layer with reference layer magnetization. Away from the AP alignment, mode-hopping limits oscillator coherence.

To appear in Phys. Rev. Lett. Note the paper accompany Suppl info

References in corpus (6)

• Bias-driven large power microwave emission from MgO-based tunnel magnetoresistance devices
• Generation linewidth of an auto-oscillator with a nonlinear frequency shift: Spin-torque nano-oscillator
• Lineshape distortion in a nonlinear auto-oscillator near generation threshold: Application to spin-torque nano-oscillators
• Microwave power generated by a spin-torque oscillator in the presence of noise
• Time-Domain Studies of Very-Large-Angle Magnetization Dynamics Excited by Spin Transfer Torques
• Direct experimental measurement of phase-amplitude coupling in spin torque oscillators