Fabrication of voltage gated spin Hall nano-oscillators

Abstract

We demonstrate an optimized fabrication process for electric field (voltage gate) controlled nano-constriction spin Hall nano-oscillators (SHNOs), achieving feature sizes of <30 nm with easy to handle ma-N 2401 e-beam lithography negative tone resist. For the nanoscopic voltage gates, we utilize a two-step tilted ion beam etching approach and through-hole encapsulation using 30 nm HfO_x. The optimized tilted etching process reduces sidewalls by 75% compared to no tilting. Moreover, the HfO_x encapsulation avoids any sidewall shunting and improves gate breakdown. Our experimental results on W/CoFeB/MgO/SiO₂ SHNOs show significant frequency tunability (6 MHz/V) even for moderate perpendicular magnetic anisotropy. Circular patterns with diameter of 45 nm are achieved with an aspect ratio better than 0.85 for 80% of the population. The optimized fabrication process allows incorporating a large number of individual gates to interface to SHNO arrays for unconventional computing and densely packed spintronic neural networks.

8 Pages, 5 Figures

References in corpus (5)

• Roadmap of spin-orbit torques
• Voltage-Gate Assisted Spin-Orbit Torque Magnetic Random Access Memory for High-Density and Low-Power Embedded Application
• Spin-orbit-torque magnonics
• Control of current-induced spin-orbit effects in a ferromagnetic heterostructure by electric field
• A Spin Hall Ising Machine

Cited by in corpus (3)

• Robust mutual synchronization in long spin Hall nano-oscillator chains
• Optothermal control of spin Hall nano-oscillators
• Voltage control of frequency, effective damping and threshold current in nano-constriction-based spin Hall nano-oscillators