A technology has been developed that can control the on-off of magnetic memory with ultra-high efficiency, and it is expected to be used in future spin-based artificial intelligence and quantum technologies.

Daegu Gyeongbuk Institute of Science and Technology (DGIST, President Lee Kun-woo) announced on the 20th that the research team led by Professor Yoo Chun-yeol of the Department of Chemical Physics succeeded in developing a technology to control the on-off of spin-orbit torque for magnetic memory operation with ultra-high efficiency by applying an electric field.

Spin-orbit torque-based magnetic memory devices are attracting attention as a next-generation technology that will overcome the limitations of existing memory devices by controlling the state of a magnetic material using electric current.

On the other hand, existing spin-orbit torque devices have limited applicability because precise control using external voltage is difficult.

Professor Yoo Chun-yeol's research team focused on the fact that in a three-layer structure of symmetric heavy metal layer-ferromagnetic layer-heavy metal layer, the spin currents generated in the upper and lower heavy metal layers are canceled out, so that spin-orbit torque does not work.

The research team experimentally demonstrated that the spin-orbit torque can be changed by more than a factor of six by controlling the spin current generated in the platinum ultra-thin film, which is a nanometer (nm-one billionth of a meter) sized upper heavy metal layer, using the ion gating technique in the structure.

This allows on-off switching of the spin-orbit torque element, and furthermore electrically programmable.It was confirmed that it can be utilized as a spin-based artificial intelligence and quantum device that can be rammed.

According to a conceptual model presented by the research team, ion gating modulates the magnitude of charge-spin interconversion in platinum ultrathin films, thereby controlling the magnitude and direction of the resulting spin current.

Based on this phenomenon, we suggest the possibility of precisely controlling the performance of spin-orbit torque devices.

“This study demonstrates that spin-orbit torque can be precisely controlled by using an external voltage, and is an important achievement that will advance the practical application of spin-based low-power logic and memory devices in the future,” said co-corresponding authors Dr. Soo-Beom Lee (currently an assistant professor at Shinshu University in Japan) and Professor Chun-Yeol Yoo.

The results of this study were published online on March 19 in the world-renowned international academic journal 'Science Advances'.