'Spin Current' Using Only Electricity... A New Chapter in Spintronics

This is a diagram illustrating the configuration of a device for measuring the Rashba-Edelstein effect.

[Asia Economy Reporter Junho Hwang] Domestic researchers have developed a core technology to commercialize the 'graphene-spin transistor,' a low-power transistor utilizing electron spin. They succeeded in generating and detecting spin current without magnetic fields or ferromagnets through the junction of graphene, a two-dimensional material composed of carbon atoms arranged in a honeycomb pattern (as thin as an atom), and transition metals. On the 18th, the Korea Advanced Institute of Science and Technology (KAIST) announced that the research results by Professor Seongjae Jo's physics team were introduced in the international academic journal ACS Nano.

The research team succeeded in increasing the spin-orbit coupling energy, where the spin of graphene and the electron's orbit interact, by more than 100 times and inducing the Rashba effect by junctioning graphene with 2H-TaS2, a transition metal and dichalcogenide material with very strong spin-orbit coupling.

The Rashba effect refers to the phenomenon where a strong spin-orbit coupling converts the electric field inside two-dimensional materials like graphene into a magnetic field. The effect of generating and detecting spin current using this is called the Rashba-Edelstein effect.

When the Rashba effect is induced in graphene, charge current and spin current can be mutually converted by the Rashba-Edelstein effect. Simply put, spin current can be generated by flowing current through graphene without magnetic fields or ferromagnets, and spin current flowing into the graphene layer can be detected through charge current or voltage measurements.

The research team also succeeded in controlling the magnitude and direction of spin current generated in the graphene heterojunction by the gate voltage, which is the voltage applied between the terminals of the transistor. This is evaluated as a groundbreaking research achievement that lays the foundation for graphene spin transistors operable without magnetic fields or ferromagnets in the future.

Professor Jo said, "This research is the first to demonstrate that spin current can be generated, detected, and controlled electrically without magnetic fields or ferromagnets in graphene heterojunctions," and predicted, "It will lead to the development of electrically operable graphene spin transistors."

He emphasized, "Especially since the experiment succeeded at room temperature, the applicability is very high," and added, "In the future, it is expected to have effects applicable not only to Korea's non-memory industry but also globally to spintronics-related physics and industries."

This content was produced with the assistance of AI translation services.