Peripheral chiral spin textures and topological Hall effect in CoSi nanomagnets
Peripheral chiral spin textures and topological Hall effect in CoSi nanomagnets
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DOI：
10.1103/physrevmaterials.5.124418
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发表时间：
2021-12
影响因子：
3.4
通讯作者：
R. Pahari;B. Balasubramanian;A. Ullah;P. Manchanda;Hiroaki Komuro;R. Streubel;C. Klewe;S. Valloppilly-S.
中科院分区：
文献类型：
--
作者：
R. Pahari;B. Balasubramanian;A. Ullah;P. Manchanda;Hiroaki Komuro;R. Streubel;C. Klewe;S. Valloppilly-S.
通过实验和理论计算研究了B20有序CoSi纳米磁体的自旋结构和输运行为。B20材料在自旋电子学中很受关注，因为它们的非中心对称晶体结构有利于非共面自旋结构，从而产生霍尔效应。然而，化学计量的块状CoSi是不稳定的，并且将室温和室温以上的磁有序与小特征尺寸相结合仍然是一个普遍的挑战。我们的CoSi纳米团簇的平均尺寸为11.6 nm，磁有序温度为330 K。第一性原理计算和X射线圆二色性实验表明，磁矩主要局限于壳的集群。CoSi纳米团簇系综表现出拓扑霍尔效应，这是解释的分析模型和微磁模拟的基础上竞争Dzyaloshinskiii-Moriya和内和团簇间交换相互作用。拓扑霍尔效应是由于在团簇的壳层中形成手征自旋织构而引起的，其表现出分数skyrmion数，因此被称为paraskyrmion（与skyrmion自旋结构密切相关）。这项研究显示了手性原子结构的纳米结构化如何创造出具有拓扑霍尔效应和高于室温的磁有序温度的自旋织构材料。
The spin structure and transport behavior of B20-ordered CoSi nanomagnets are investigated experimentally and by theoretical calculations. B20 materials are of interest in spin electronics because their noncentrosymmetric crystal structure favors noncoplanar spin structures that yield a contribution to the Hall effect. However, stoichiometric bulk CoSi is nonmagnetic, and combining magnetic order at and above room temperature with small feature sizes has remained a general challenge. Our CoSi nanoclusters have an average size of 11.6 nm and a magnetic ordering temperature of 330 K. First-principle calculations and x-ray circular dichroism experiments show that the magnetic moment is predominantly confined to the shells of the clusters. The CoSi nanocluster ensemble exhibits a topological Hall effect, which is explained by an analytical model and by micromagnetic simulations on the basis of competing Dzyaloshinskii-Moriya and intra- and intercluster exchange interactions. The topological Hall effect is caused by formation of chiral spin textures in the shells of the clusters, which exhibit fractional skyrmion number and are therefore termed as paraskyrmions (closely related to skyrmion spin structures). This research shows how nanostructuring of a chiral atomic structure can create a spin-textured material with a topological Hall effect and a magnetic ordering temperature above room temperature.