Professor Gyung-Min Choi's research team in the Department of Energy Science at Sungkyunkwan University (President Ji-Bum Yoo) has announced the development of a 70 GHz ultra-high-speed spin device based on antiferromagnetic materials in collaboration with Professor Kyung-Jin Lee's research team at KAIST. This technology is attracting attention as a core principle for the development of ultra-high-speed magnetic memory.

Magnetic memory (MRAM) stores information as “0” and “1” based on the magnetization direction of a magnetic material, and the spin-torque  is used to electrically control this magnetization direction. Spin-torque is a phenomenon in which the spin of electrons is absorbed into the magnetization of a ferromagnet when the electrons' spin is injected into the ferromagnet, and it is a physical principle for the transfer of angular momentum within the material (Figure 1). In ferromagnetic materials, the operating speed by spin torque is limited to the 1 GHz level due to the low resonance frequency of the material. This research team has developed a spin-torque device that operates at 70 GHz, exceeding the speed limit of conventional magnetic memory, by utilizing Mn3Sn, an antiferromagnetic material with a high resonance frequency (Figure 2).

This study revealed how spins can be absorbed in chiral antiferromagnets, where the atomic structure has a rotating form. In particular, it showed that the spin coherence length, which is the distance over which spins are absorbed, is very long compared to conventional ferromagnets. This long spin coherence length has the effect of increasing spin torque efficiency (Figure 3).

Professor Choi explained, "This research provides a concrete understanding of the spin-torque phenomenon between spin current and antiferromagnets, a discovery that enables the development of high-speed memory at the 70 GHz level."

The findings of this research were published in the world-renowned international academic journal Nature Nanotechnology on February 3rd. This research was was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST).

※ Title: Spin-torque-driven gigahertz magnetization dynamics in the non-collinear

antiferromagnet Mn3Sn

※ Journal: Nature Nanotechnology (IF: 38.1)

※ Link: https://www.nature.com/articles/s41565-025-01859-7

▲[Figure 1] Spin-torque-driven operation of magnetic memory (MRAM)

▲[Figure 2] Spin-torque driven 70 GHz pecession of Mn3Sn

▲[Figure 3] Spin-coherence length in chiral antiferromagent

SKKU Prof. Gyung-Min Choi (left), KAIST Prof. Kyung-Jin Lee (right)