Researchers from Northwestern University, in collaboration with researchers from China, Italy and France, developed a new SOT-MRAM device structure that enables deterministic switching without any need for bias magnetic fields.

The new approach, unlike most earlier methods, can be scaled to large wafers with good uniformity, since it doesn't rely on having a structural asymmetry in the device. SOT-MRAM devices based on this structure could be faster and more energy-efficient than current designs.

The new SOT-MRAM device uses a material which is based on a multi-layered stack of ultrathin films of CoTb, an alloy of the elements cobalt and terbium. In addition to demonstrating that SOT switching in this layered material does not require any external magnetic fields, the authors showed that it is also one of the most efficient SOT materials reported to date.