Spin-orbit torque (SOT) induced magnetization switching is a complex technology currently of great interest for various spintronic applications. It can potentially revolutionize nonvolatile embedded memory, such as magnetic random access memory (MRAM), logic devices, and true random number generators. These devices require a few nanometer-thick materials with perpendicular magnetic anisotropy (PMA) for high bit density, significant SOT efficiency to reduce writing current and energy consumption, and external field-free switching. Above all, the SOT materials must be semiconductor fabrication-friendly. However, only a few material sets and their heterostructures fulfill the requirements. In our recent research, we have faced the challenge of exploring various alloying elements, including Ta, N, V, Si, and Ti, in the β-phase W matrix as a spin-current-generating layer with enhanced SOT efficiencies. We employ first-principles energy-band calculations to narrow down the compositional ranges where we can obtain high-spin Hall conductivity values. Then, we deposit nonmagnetic/ferromagnetic heterostructures and pattern them into devices. For example, we confirm that the heterostructure consisting of β-W-Si (4 at%)/CoFeB exhibits PMA, a high damping-like SOT efficiency (~0.58), and low longitudinal resistivity (~135 μΩ cm). The heterostructures withstand 500ºC post-deposition heat treatment. Furthermore, we estimate write power consumption 10 times lower than that of the heterostructure based on pristine β-W and other materials. These findings highlight the complexity of the task and the potential for significant advances in next-generation MRAM applications.
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More information :https://www.spintec.fr/seminar-designing-high-efficiency-spin-orbit-torque-materials-from-beta-w-alloy-engineering-to-low-power-mram-switching/​​
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Visioconference : https://univ-grenoble-alpes-fr.zoom.us/j/98769867024?pwd=dXNnT3RMeThjYStybGVQSUN0TVdJdz09​​​
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