Researchers from National Taiwan University demonstrate that chalcogenide material BiTe with non-epitaxial structure can give rise to a giant spin Hall ratio and SOT efficiency (~ 200%) without obvious evidence of topologically-protected surface state (TSS).

BiTe material system for SOT-MRAM schema (NUS)

The researchers explain that a clear thickness-dependent increase of the SOT efficiency indicates that the origin of this effect is from the bulk spin-orbit interaction of such materials system. Efficient current-induced switching through SOT is also demonstrated with a low zero-thermal critical switching current density (~ 6×105 A/cm2).

In SOT-MRAM, or spin-orbit torque MRAM, the switching of the free magnetic layer is done by injecting an in-plane current in an adjacent SOT layer, unlike STT-MRAM where the current is injected perpendicularly into the magnetic tunnel junction and the read and write operation is performed through the same path. SOT-MRAM promises to be faster, denser and more efficient. In 2018 researchers from Imec fabricated SOT-MRAM devices on 300mm wafers using CMOS compatible processes, for the first time.

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