近日，德国马克斯·普朗克物质结构与动力学研究所的Philip J. W. Moll与瑞士苏黎世大学的Titus NeupertMoll等人合作并取得新进展。经过不懈努力，他们揭示笼目金属CsV3Sb5中倾覆点的关联有序。相关研究成果已于2024年1月31日在国际知名学术期刊《自然—物理学》上发表。
据悉，自发对称性破缺是量子物质和更普遍的物理现象的核心。然而，由于应变等不完美因素，特别是在多个电子序相互竞争的情况下，确定被破坏的确切对称性可能具有挑战性。在某些笼目系统中的电荷有序就是一个例子，在这些系统中，由于相互矛盾的测量结果，轨道电流的向列性和通量序的存在仍存在不确定性。
该研究团队通过制造笼目家族成员CsV3Sb5的高度对称样品并测量其输运性质，成功澄清了关于电荷有序的争议。研究结果显示，在未受扰动的材料中，任何温度下都不存在可测量的各向异性。然而，当存在弱磁场或应变时，会出现明显的面内输运各向异性。对称性分析进一步表明，垂直磁场确实可以通过诱导与更常规键序共存的磁通序，从而导致面内各向异性。这项研究结果为笼目金属中备受争议的电荷有序提供了统一的图景，并强调了在微观尺度上识别破缺对称性时，材料控制的必要性。
附：英文原文
Title: Correlated order at the tipping point in the kagome metal CsV3Sb5
Author: Guo, Chunyu, Wagner, Glenn, Putzke, Carsten, Chen, Dong, Wang, Kaize, Zhang, Ling, Gutierrez-Amigo, Martin, Errea, Ion, Vergniory, Maia G., Felser, Claudia, Fischer, Mark H., Neupert, Titus, Moll, Philip J. W.
Issue&Volume: 2024-01-31
Abstract: Spontaneously broken symmetries are at the heart of many phenomena of quantum matter and physics more generally. However, determining the exact symmetries that are broken can be challenging due to imperfections such as strain, in particular when multiple electronic orders are competing. This is exemplified by charge order in some kagome systems, where evidence of nematicity and flux order from orbital currents remains inconclusive due to contradictory measurements. Here we clarify this controversy by fabricating highly symmetric samples of a member of this family, CsV3Sb5, and measuring their transport properties. We find that a measurable anisotropy is absent at any temperature in the unperturbed material. However, a pronounced in-plane transport anisotropy appears when either weak magnetic fields or strains are present. A symmetry analysis indicates that a perpendicular magnetic field can indeed lead to in-plane anisotropy by inducing a flux order coexisting with more conventional bond order. Our results provide a unifying picture for the controversial charge order in kagome metals and highlight the need for materials control at the microscopic scale in the identification of broken symmetries.
DOI: 10.1038/s41567-023-02374-z
Source: https://www.nature.com/articles/s41567-023-02374-z