On April 27, a co-research group consisting of Professor Byong-Guk Park from the Department of Materials Science and Engineering and Professor Kyung-Jin Lee from the Department of Physics announced that their team has developed a new spin-based technology that can dramatically reduce energy consumption of a Spin Orbital Torque-Magnetoresistive Random Access Memory (SOT-MRAM). This is a high-speed non-volatile RAM identified as a next-generation memory device.

Random-access memory (RAM) is a computer memory device that stores data and machine code. It enables read and write functions regardless of its physical location. Data in RAM is stored as current flows and is interpreted through measuring the resistance inside particular cells of RAM. However, conventional RAMs are usually volatile and not byte-addressable, signifying that it is hard to access data. Henceforth, scientists have argued that MRAM that complements such defects will surpass the conventional technologies. Instead of storing data in current flows, MRAM stores data in magnetic storage created by two permanent magnet plates having a magnetic tunnel junction — analogous to cells in conventional RAM devices. However, this device requires an external magnetic field for magnetization switching, which consumes too much operating power, showing low switching efficiency.

Professor Park and Lee’s team was able to experimentally prove that spin currents with spin polarization in x, y, and z directions flow inside a new spin material structure of a single crystal ferromagnetic metal bilayer. From this finding, the research team succeeded in developing a technology that dramatically reduces power consumption for switching current. They found a condition that maximizes spin torque efficiency by controlling the magnetization and current direction. This new finding and application to increase energy efficiency of SOT-MRAM are expected to stimulate its commercialization and further technological innovation. It is likely that it will be used for mobile, wearable, and IoT devices’ memory components that require low power consumption, high-speed operation, and non-volatile characteristics.  

Dr. Jeong Chun Ryu, the first author of this paper, stated that “this study has demonstrated that it can simultaneously generate and control spin currents in multiple directions in magnetic memory and it can be used to develop low-power spintronic devices.” Professor Park and Lee’s research team published their work in the international journal Nature Electronics with title “Efficient spin-orbit torque in magnetic trilayers using all three polarizations of a spin current.