近日，日本东京大学的S. Seki&H. Yoshimochi及其研究团队取得一项新进展。经过不懈努力，他们对中心对称磁体中介子和斯基子晶体的多步拓扑相变进行研究。相关研究成果已于2024年4月1日在国际知名学术期刊《自然—物理学》上发表。

该研究团队展示了在中心对称磁铁GdRu₂Ge₂中，多种介子和斯基子晶体状态之间发生的多步拓扑相变。这些相变是由Ruderman-Kittel-Kasuya-Yosida相互作用在不相等波矢量上的竞争所驱动的。这些发现揭示了即便是简单的中心对称磁铁，只要存在竞争相互作用，也能成为实现丰富多样的磁性准粒子的潜在材料平台。这些准粒子拥有独特的对称性和拓扑结构，且其稳定性可以通过多种外部刺激进行调节。

据悉，拓扑自旋织构，例如斯格明子和麦韧，因其作为高密度磁信息器件潜在构建块的特性，最近备受瞩目。然而，如何有效控制不同类型准粒子间的相变仍是一大挑战。目前，这些相变主要出现在少数非中心对称系统中，这些系统由Dzyaloshinskii-Moriya相互作用所驱动。

附：英文原文

Title: Multistep topological transitions among meron and skyrmion crystals in a centrosymmetric magnet

Author: Yoshimochi, H., Takagi, R., Ju, J., Khanh, N. D., Saito, H., Sagayama, H., Nakao, H., Itoh, S., Tokura, Y., Arima, T., Hayami, S., Nakajima, T., Seki, S.

Issue&Volume: 2024-04-01

Abstract: Topological swirling spin textures, such as skyrmions and merons, have recently attracted much attention as potential building blocks for high-density magnetic information devices. Controlling the transformation between different types of these quasiparticles is an important challenge. To date, these transitions have mostly been limited to a few non-centrosymmetric systems, where they are driven by the Dzyaloshinskii–Moriya interaction. Here we demonstrate multistep topological transitions among a variety of meron and skyrmion crystal states in a centrosymmetric magnet GdRu₂Ge₂. These are governed by the competition between Ruderman–Kittel–Kasuya–Yosida interactions at inequivalent wave vectors. These findings demonstrate that even a simple centrosymmetric magnet with competing interactions can be a promising material platform to realize a richer variety of magnetic quasiparticles with distinctive symmetry and topology, whose stability can be tuned by various external stimuli.

DOI: 10.1038/s41567-024-02445-9

Source: https://www.nature.com/articles/s41567-024-02445-9