Influence of MgO Tunnel Barrier Thickness on the Output Power of Three-Terminal Spin Hall Nano-Oscillators

Magnetic tunnel junction nanopillar devices were patterned into three-terminal spin Hall nano-oscillators starting from a 200 mm wafer with an MgO barrier wedge with a nominal thickness variation between 0.72 and 1.36 nm. The resulting devices, with R × A values in the range between 1 and 110 Ω · μm
²
, were characterized in the frequency domain in an attempt to optimize the MgO barrier thickness with respect to the nano-oscillators output power. While all the devices exhibit oscillations, the integrated matched output power reaches a maximum of 12.5 nW for an R × A of 34 Ω · μm
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with a nominal MgO thickness of 1.2 nm.