Current-Induced Nucleation and Annihilation of Magnetic Skyrmions at Room Temperature in a Chiral Magnet.

Yu, Xiuzhen; Morikawa, Daisuke; Tokunaga, Yusuke; Kubota, Masashi; Kurumaji, Takashi; Oike, Hiroshi; Nakamura, Masao; Kagawa, Fumitaka et al. · Adv Mater · 2017

basic_science · Level V

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Abstract

A magnetic skyrmion is a nanometer-scale magnetic vortex carrying an integer topological charge. Skyrmions show a promise for potential application in low-power-consumption and high-density memory devices. To promote their use in applications, it is attempted to control the existence of skyrmions using low electric currents at room temperature (RT). This study presents real-space observations for the current-induced formation and annihilation of a skyrmion lattice (SkL) as well as isolated skyrmions in a microdevice composed of a thin chiral magnet Co<sub>8</sub> Zn<sub>9</sub> Mn<sub>3</sub> with a Curie temperature, T<sub>C</sub> ≈ 325 K, above RT. It is found that the critical current for the manipulation of Bloch-type skyrmions is on the order of 10<sup>8</sup> A m<sup>-2</sup> , approximately three orders of magnitude lower than that needed for the creation and drive of ferromagnetic (FM) domain walls in thin FM films. The in situ real-space imaging also demonstrates the dynamical topological transition from a helical or conical structure to a SkL induced by the flow of DC current, thus paving the way for the electrical control of magnetic skyrmions.