Spin torque nano-oscillators with tilted magnetic anisotropy

Area of Science:

• Spintronics
• Materials Science
• Microwave Engineering

Background:

• Spin-torque nano-oscillators (STNOs) are key for wireless communication and neuromorphic computing.
• Tilted magnetic anisotropy (TMA) in STNOs theoretically offers superior performance, but experimental data is lacking.

Purpose of the Study:

• To experimentally investigate nanocontact STNOs (NC-STNOs) with a TMA free layer.
• To explore the magnetization dynamics and microwave emission properties of these TMA-based STNOs.

Main Methods:

• Fabrication and experimental measurement of NC-STNOs with a [Co/Pd]/Cu/[Co/Ni]/NiFe multilayer structure.
• Integration of experimental data with micromagnetic simulations to analyze magnetization dynamics.

Main Results:

• Observed coexistence and transitions between distinct dynamical modes, leading to multi-frequency microwave emission.
• Identified a unique droplet-like propagating spin-wave (PSW) mode with dual characteristics.
• Demonstrated significantly greater synchronization distances for the droplet-like PSW mode compared to perpendicular magnetic anisotropy (PMA)-based STNOs.

Conclusions:

• TMA-based STNOs exhibit rich magnetization dynamics not seen in conventional systems.
• The droplet-like PSW mode is crucial for achieving long-range synchronization in STNO arrays.
• Findings pave the way for synchronized STNO arrays in practical applications.