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Xi Chen a , Randall Victora b Dept. of Physics a and Dept. of Electrical & Computer b Engineering, University of M

Free layer. Fixed layer. Spin-wave mediated interaction between spin torque oscillators. Coupling constant:. Xi Chen a , Randall Victora b Dept. of Physics a and Dept. of Electrical & Computer b Engineering, University of Minnesota, Minneapolis, USA.

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Xi Chen a , Randall Victora b Dept. of Physics a and Dept. of Electrical & Computer b Engineering, University of M

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  1. Free layer Fixed layer Spin-wave mediated interaction between spin torque oscillators Coupling constant: Xi Chena, Randall Victorab Dept. of Physicsa and Dept. of Electrical & Computerb Engineering, University of Minnesota, Minneapolis, USA • Spin torque effect provides new ways to manipulate magnetization dynamics and opens up many interesting applications, e.g. MRAM. • Spin torque can be used to generate steady magnetic precession by canceling the intrinsic damping torque, which makes a microwave oscillator at nanoscale possible. • The main challenge is to increase the power generated by a spin torque oscillator (STO), which is too small for application at present. • Multiple STO array phase locked together is proposed to enhance the power. The phase lock between STOs is believed to be induced by spinwave and has been demonstrated experimentally. • In this work, we study the phase locking mechanism between STOs using analytical tools and micromagnetic simulation. • We consider a STO in nano-contact geometry placed on a magnetic thin film (permalloy). • The magnetization dynamics is modeled by Landau-Lifshitz-Gilbert (LLG) equation: • Micormagnetic simulation is performed and clearly shows the spinwave excited by current through contact: • Frequency vs. current, as compared to experiment: • Consider two STOs placed on the same film: • The LLG equation can be rewritten: • Fix I1 at 4.6 mA and vary I2: Introduction • Coupling K oscillates with contact separation. • Positive K: in-phase, enhanced power. • Negative K: out-phase, reduced power. Single Oscillator & Spinwave Excitation • Oscillatory coupling: theory vs. simulation: Theory and Simulation of Phase Locked Oscillators Summary • STOs interact through spinwaves excited by the current. • The coupling between STOs oscillates with distance, with the period being wavelength. • The behavior of the coupling is crucial for the output power of a STO array.

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