Magnetic Bubblecade Memory Based on Chiral Domain Walls

Nature, Scientific Reports has published an article written by Kyoung-Woong Moon,Center for Nanometrology, Korea Research Institute of Standards and Science, Daejeon, Korea , Duck-Ho Kim, CSO and Department of Physics, Seoul National University, Seoul, Korea, Sang-Cheol Yoo, CSO and Department of Physics, Seoul National University, Seoul, Korea, Spin Convergence Research Center, Korea Institute of Science and Technology, Seoul, Korea, Soong-Geun Je,CSO and Department of Physics, Seoul National University, Seoul 151-742, Republic of Korea , Byong Sun Chun, Center for Nanometrology, Korea Research Institute of Standards and Science, Daejeon, Korea , Wondong Kim,Center for Nanometrology, Korea Research Institute of Standards and Science, Daejeon, Korea, Byoung-Chul Min, Spin Convergence Research Center, Korea Institute of Science and Technology, Seoul, Korea, Chanyong Hwang, Center for Nanometrology, Korea Research Institute of Standards and Science, Daejeon, Korea, and Sug-Bong Choe, CSO and Department of Physics, Seoul National University, Seoul, Korea.

(a) Illustration of a bubble domain (bright circle) and the DW (grey ring), surrounded
by a domain of opposite magnetization (dark area). The red symbols and arrows
indicate the direction of the magnetization inside the DW and domains.
(b) Asymmetric DW-energy distribution under an in-plane magnetic field +H_x
(green arrow), as visualized by the color contrast of the arrows on the DW
according to the scale bar at the bottom. (c) Asymmetric DW expansion
under a magnetic field H ( = (+H_x,+H_z)) with a tilting angle θ.
(d) Asymmetric DW-energy distribution under the reversed in-plane magnetic field −H_x.
(e) Asymmetric DW shrinkage under the reversed magnetic field (−H_x,−H_z).
The dashed circles represent the previous DW positions.

Abstract: “Unidirectional motion of magnetic domain walls is the key concept underlying next-generation domain-wall-mediated memory and logic devices. Such motion has been achieved either by injecting large electric currents into nanowires or by employing domain-wall tension induced by sophisticated structural modulation. Herein, we demonstrate a new scheme without any current injection or structural modulation. This scheme utilizes the recently discovered chiral domain walls, which exhibit asymmetry in their speed with respect to magnetic fields. Because of this asymmetry, an alternating magnetic field results in the coherent motion of the domain walls in one direction. Such coherent unidirectional motion is achieved even for an array of magnetic bubble domains, enabling the design of a new device prototype—magnetic bubblecade memory—with two-dimensional data-storage capability.“