Writing skyrmions for room temperature and zero field

MAR 26, 2018

A new way to write magnetic skyrmions on the surface of Pt/Co/Ta structures, that are stable at room temperature and zero fields, uses a magnetic force microscope.

Yuen Yiu

DOI: 10.1063/1.5030841

Writing skyrmions for room temperature and zero field internal name — Writing skyrmions for room temperature and zero field lead image

Skyrmions are topological, protected magnetic states with sizes as small as a nanometer across, making them attractive as a possible next-generation technology for applications such as magnetic storage and spintronics. For practical applications, however, skyrmions need to be stable at zero magnetic field and room temperature. Room temperature skyrmions in sputtered multilayer films were recently discovered and provided a substantial boost toward this goal. To stabilize the skyrmions, these materials generally require either an applied magnetic field or a geometrical constraint.

Researchers report in Applied Physics Letters a new, straightforward way to create room temperature and zero field stable skyrmions on the surface of Pt/Co/Ta multilayers. By choosing the tapping mode of a magnetic force microscope (MFM), they used the local field around the MFM’s tip to “cut” a labyrinth domain on the surface of the material into stable skyrmions, with even only a single scan.

The skyrmions, created on the surface of Pt/Co/Ta multilayers, were stable at room temperature as well as in zero magnetic fields. Their corresponding simulations showed that the skyrmion lattice is at the lowest energy phase, meaning that once created, the skyrmion lattice state remains as a metastable state.

The orientation of their skyrmions were further characterized as Néel-type, where the spins rotate in the radial planes from the core out toward the edges. Bloch-type skyrmions, on the other hand, feature spins that rotate along the tangential planes. This study opens a new avenue for the creation and study of skyrmion lattices in thin films.

Source: “Direct writing of room temperature and zero field skyrmion lattices by a scanning local magnetic field,” by Senfu Zhang, Junwei Zhang, Qiang Zhang, Craig Barton, Volker Neu, Yuelei Zhao, Zhipeng Hou, Yan Wen, Chen Gong, Olga Kazakova, Wenhong Wang, Yong Peng, Dmitry A. Garanin, Eugene M. Chudnovsky, and Xixiang Zhang, Applied Physics Letters (2018). The article can be accessed at https://doi.org/10.1063/1.5021172 .