Optimal angle of magnetic field for magnetic bubblecade motion

최근 교류 자기장을 이용하여 Bubblecade (Sci. Rep. 5, 9166 (2015). 최석봉 교수 연구실)를 이용해 새로운 2차원 차세대 메모리가 제안되었다. 여기에서 Bubblecade의 속력은 메모리의 동작 속도에 직접적으로 역할을해, 최적화는 필수적이다. 본 연구진은 특정 각도에서 Bubblecade가 최대 속도로 움직이는 것을 관측하였고, 이 각도는 걸어준 자기장값에 의해 결정되는 것을 이론적으로 증명하였다. 이와 같은 속도 최적화는 Skyrmion-like-Bubblecade을 이용한 자성 메모리 소자 개발에 중요한 역할을 할 것으로 기대된다. 본 연구 성과는 Scientific Reports에 6월 16일 출간되었다.

Abstract: Unidirectional motion of magnetic structures such as the magnetic domain and domain walls is a key concept underlying next-generation memory and logic devices. As a potential candidate of such unidirectional motion, it has been recently demonstrated that the magnetic bubblecade—the coherent unidirectional motion of magnetic bubbles—can be generated by applying an alternating magnetic field. Here we report the optimal configuration of applied magnetic field for the magnetic bubblecade. The tilted alternating magnetic field induces asymmetric expansion and shrinkage of the magnetic bubbles under the influence of the Dzyaloshinskii-Moriya interaction, resulting in continuous shift of the bubbles in time. By examining the magnetic bubblecade in Pt/Co/Pt films, we find that the bubblecade speed is sensitive to the tilt angle with a maximum at an angle, which can be explained well by a simple analytical form within the context of the domain-wall creep theory. A simplified analytic formula for the angle for maximum speed is then given as a function of the amplitude of the alternating magnetic field. The present results provide a useful guideline of optimal design for magnetic bubblecade memory and logic devices.

Authors: Duck-Ho Kim(서울대), Kyoung-Woong Moon(한국표준과학연구원), Sang-Cheol Yoo(서울대,한국과학기술연구원), Dae-Yun Kim(서울대), Buoung-Chul Min (한국과학기술연구원), Chanyong Hwang(한국표준과학연구원), and Sug-Bong Choe(서울대)★

Scientific Reports 7, 3660 (2017)
doi:10.1038/s41598-017-03832-4
Published online: 16 June 2017.

https://www.nature.com/articles/s41598-017-03832-4