Fukuoka, Japan—Publishing in npj Spintronics , a research team led by Kyushu University have developed a new fabrication method for energy-efficient magnetic random-access memory (MRAM) using a new material called thulium iron garnet (TmIG) that has been attracting global attention for its ability to enable high-speed, low-power information rewriting at room temperature. The team hopes their findings will lead to significant improvements in the speed and power efficiency of high-computing hardware, such as those used to power generative AI.
The rapid spread of generative AI has made the power demand from data centers a global issue, creating an urgent need to improve the energy efficiency of the hardware that runs the technology.
"Spin-orbit torque, or SOT, is an important technology that can potentially help with this problem. It is a method of memory storage that uses electricity, as opposed to magnets, to control the orientation of microscopic magnets on a thin film of material in a device, allowing us to produce faster MRAM," explains Associate Professor Naoto Yamashita of Kyushu University's Faculty of Information Science and Electrical Engineering , the corresponding author of the study. "A promising SOT material is thulium iron garnet (TmIG). It was originally developed in Japan in 2012 and can produce SOT when a film of platinum is placed on it and a current is applied. It is quite a groundbreaking material."
However, TmIG requires a high-quality thin film to be a viable memory device. Previous methods of coating have shown to be costly and technically difficult. In their new findings Yamashita and his team succeeded in producing these films using an established mass production method called 'on-axis sputtering.' In this process, atoms are 'knocked-out' of the film material and then deposited on the substrate layer by layer.
"We utilized this method to deposit a very thin three nanometer layer of platinum on the TmIG. Follow up tests showed that we could alter its memory data (magnetic orientation) by simply passing a small current through it," continues Yamashita. "The data writing efficiency was 0.7 x 1011 A/m2 and is comparable to films fabricated using conventional methods."
The team's new findings mark an important step in bridging the gap between basic and applied research on high-performance memory technology.
"We are already developing functional devices that take advantage of our new findings," concludes Yamashita. "We hope to leverage our work to build a more sustainable information society."
