Gigantic current control of coercive field and magnetic memory based on nm-thin ferromagnetic van der Waals Fe3GeTe2

자성 반데르발스 물질은 박제근 교수 그룹이 2016년 세계 최초로 발견하면서 세계적인 각광을 받고 있는 연구분야이다. 이 연구에서는 Fe3GeTe2의 자기위상학적인 성질을 이용하여 새로운 형태의 자기 소자를 구현하였다. 이 소자의 특징은 비휘발성이면서 기존에 알려진 경쟁 물질보다 1000배 정도 낮은 저전력으로 구동되는 획기적인 성질을 가지고 있다.

Controlling magnetic states by a small current is essential for the next-generation of energy-efficient spintronic devices. However, it invariably requires considerable energy to change a magnetic ground state of intrinsically quantum nature governed by fundamental Hamiltonian, once stabilized below a phase transition temperature. We report that surprisingly an in-plane current can tune the magnetic state of nm-thin van der Waals ferromagnet Fe3GeTe2 from a hard magnetic state to a soft magnetic state. It is the direct demonstration of the current-induced substantial reduction of the coercive field. This surprising finding is possible because the in-plane current produces a highly unusual type of gigantic spin-orbit torque for Fe3GeTe2, which is directly related to the Berry curvature of Fe3GeTe2 and so its band topology. And we further demonstrate a working model of a new nonvolatile magnetic memory based on the principle of our discovery in Fe3GeTe2, controlled by a much smaller current. Our findings open up a new window of exciting opportunities for magnetic van der Waals materials with potentially huge impacts on the future development of spintronic and magnetic memory.

참여 연구원: Kaixuan Zhang, 이유진, Matt Coak, 김정현, 황인호, 손수한, 신제철, 김도헌, 박제근

Link1: https://doi.org/10.1002/adma.202004110