Energy-Efficient <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi mathvariant="normal">W</mml:mi><mml:mrow><mml:mn>100</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Ta</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mo>/</mml:mo></mml:math>Co-Fe-B/MgO Spin Hall Nano-Oscillators
Nilamani Behera, Himanshu Fulara, Lakhan Bainsla, Akash Kumar, Mohammad Zahedinejad, Afshin Houshang, Johan Åkerman
Abstract
We investigate a W-Ta alloying route to reduce the auto-oscillation threshold current densities and the power consumption of nanoconstriction based spin Hall nano-oscillators. Using spin-torque ferromagnetic resonance measurements on microbars of ${\mathrm{W}}_{100\ensuremath{-}x}{\mathrm{Ta}}_{x}$(5 nm)/$\mathrm{Co}$-$\mathrm{Fe}$-$\mathrm{B}$($t$)/$\mathrm{Mg}\mathrm{O}$ stacks with $t=1.4$, 1.8, and 2.0 nm, we measure a substantial improvement in both the spin-orbit torque efficiency and the spin Hall conductivity. We demonstrate a 34% reduction in auto-oscillation threshold current density, which translates into a 64% reduction in power consumption as compared with pure W-based spin Hall nano-oscillators. Our work demonstrates the promising aspects of W-Ta alloying for the energy-efficient operation of emerging spintronic devices.