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arXiv 2303.04879cond-mat.mtrl-scicond-mat.str-el
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插层范德华材料中由非共面反铁磁序诱导的自发拓扑霍尔效应

Spontaneous topological Hall effect induced by non-coplanar antiferromagnetic order in intercalated van der Waals materials

H. Takagi, R. Takagi, S. Minami, T. Nomoto, K. Ohishi, M. -T. Suzuki, Y. Yanagi, M. Hirayama, N. D. Khanh, K. Karube, H. Saito, D. Hashizume, R. Kiyanagi, Y. To… 展开作者

H. Takagi, R. Takagi, S. Minami, T. Nomoto, K. Ohishi, M. -T. Suzuki, Y. Yanagi, M. Hirayama, N. D. Khanh, K. Karube, H. Saito, D. Hashizume, R. Kiyanagi, Y. Tokura, R. Arita, T. Nakajima, S. Seki

备注：
to appear in Nature Physics
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AI总结：

本研究在插层范德华材料 CoTa3S6 和 CoNb3S6 中发现了全进全出型非共面反铁磁序，揭示了标量自旋手性诱导的自发拓扑霍尔效应，为补偿反铁磁体的电学读取与写入提供了新平台。

摘要：

在铁磁体中，电流通常会诱导与磁化强度成正比的横向霍尔电压（反常霍尔效应），这常被用于上下自旋态的电学读取。虽然这些性质通常不期望在反铁磁体中出现，但近期的理论研究预测，具有有限标量自旋手性（即相邻自旋张成的立体角）的非共面反铁磁序，即使在没有净磁化或外加磁场的情况下，也往往能诱导出巨大的自发霍尔效应。这种现象，即自发拓扑霍尔效应，有望用于反铁磁态的高效电学读取，但由于缺乏承载此类奇异磁性的合适材料，其实验验证长期难以实现。在此，我们报告了在三角晶格化合物 CoTa3S6 和 CoNb3S6 中发现的全进全出型非共面反铁磁序，这是通过基于极化中子散射实验的详细磁结构分析以及系统的第一性原理计算完成的。据报道，这些化合物尽管净磁化极小，却呈现出反常巨大的自发霍尔效应；我们的分析表明，这可以用拓扑霍尔效应很好地解释，该效应源于非共面反铁磁序中与标量自旋手性相关的虚拟磁场。本研究结果表明，标量自旋手性机制可为在补偿反铁磁体中实现巨大自发霍尔响应提供一条有前景的途径，并凸显了插层范德华磁体作为一个独特的准二维材料平台，能够以各种非平庸方式实现非共面反铁磁畴的电学读取及可能的写入。

英文摘要：

In ferromagnets, electric current generally induces transverse Hall voltage in proportion to magnetization (anomalous Hall effect), and it is frequently used for electrical readout of the up and down spin states. While these properties are usually not expected in antiferromagnets, recent theoretical studies predicted that non-coplanar antiferromagnetic order with finite scalar spin chirality (i.e. solid angle spanned by neighboring spins) can often induce large spontaneous Hall effect even without net magnetization or external magnetic field. This phenomenon, i.e. spontaneous topological Hall effect, can potentially be used for the efficient electrical readout of the antiferromagnetic states, but its experimental verification has long been elusive due to the lack of appropriate materials hosting such exotic magnetism. Here, we report the discovery of all-in-all-out type non-coplanar antiferromagnetic order in triangular lattice compounds CoTa3S6 and CoNb3S6, by performing the detailed magnetic structure analysis based on polarized neutron scattering experiments as well as systematic first-principles calculations. These compounds are reported to host unconventionally large spontaneous Hall effect despite their vanishingly small net magnetization, and our analysis revealed that it can be well explained in terms of topological Hall effect, which originates from the fictitious magnetic field associated with scalar spin chirality in non-coplanar antiferromagnetic orders. The present results indicate that the scalar spin chirality mechanism can offer a promising route to realize giant spontaneous Hall response even in compensated antiferromagnets, and highlight intercalated van der Waals magnets as an unique quasi-two-dimensional material platform to enable various nontrivial manner of electrical reading and possible writing of non-coplanar antiferromagnetic domains.

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