  Spin-Orbit Torque (SOT) Magnetic Random-Access Memory (MRAM) devices offer
improved power efficiency, nonvolatility, and performance compared to static
RAM, making them ideal, for instance, for cache memory applications. Efficient
magnetization switching, long data retention, and high-density integration in
SOT MRAM require ferromagnets (FM) with perpendicular magnetic anisotropy (PMA)
combined with large torques enhanced by Orbital Hall Effect (OHE). We have
engineered PMA [Co/Ni]$_3$ FM on selected OHE layers (Ru, Nb, Cr) and
investigated the potential of theoretically predicted larger orbital Hall
conductivity (OHC) to quantify the torque and switching current in
OHE/[Co/Ni]$_3$ stacks. Our results demonstrate a $\sim$30\% enhancement in
damping-like torque efficiency with a positive sign for the Ru OHE layer
compared to a pure Pt, accompanied by a $\sim$20\% reduction in switching
current for Ru compared to pure Pt across more than 250 devices, leading to
more than a 60\% reduction in switching power. These findings validate the
application of Ru in devices relevant to industrial contexts, supporting
theoretical predictions regarding its superior OHC. This investigation
highlights the potential of enhanced orbital torques to improve the performance
of orbital-assisted SOT-MRAM, paving the way for next-generation memory
technology.
