Proposal of a Single Nano-Magnet Memory Device

Abstract

We propose a non-volatile memory device using ferromagnetic (FM) contacts fabricated on a channel exhibiting spin-momentum locking observed in diverse materials with spin-orbit coupling like heavy metals and topological insulators. The writing is enabled by the current induced spin-orbit torque, which has been used previously to switch the storage layer of a magnetic tunnel junction (MTJ). The reading is enabled by a relatively lower current-induced spin voltage measurement through the FM contact, which is high or low depending on the magnetization direction for a particular current direction. This new read mechanism significantly reduces the fabrication difficulties compared with MTJ-based designs. Simpler interconnects and control circuits can be used, since both read and write currents share the same path. Our proposal offers on-cell reference voltage generation with a normal metal contacton the channel at the same position as the FM, which is expected to improve the performance in a large array. The estimated read signal based on available materials is smaller compared with MTJ, but the noise is also expected to be smaller in our metallic device compared with those involving tunnel barriers.