近日，意大利博洛尼亚大学的Domenico Di Sante与意大利国立研究委员会(Consiglio Nazionale delle Ricerche)材料研究所的Federico Mazzola以及德国维尔茨堡大学的Giorgio Sangiovanni等人合作，并取得了一项新进展。经过不懈努力，他们探究了双层kagome金属中的平带分离和鲁棒自旋Berry曲率。相关研究成果已于2023年5月18日在国际知名学术期刊《自然—物理学》上发表。
该研究小组对XV6Sn6 Kagome家族的自旋和电子结构进行了探索。他们获得了在布里渊区中心存在有限自旋Berry曲率贡献的证据，其中近乎平坦的带由于自旋轨道耦合而与分散的Dirac带分离。此外，他们还在ScV6Sn6的电荷密度波区域进一步研究了自旋Berry曲率，并发现它对温度驱动的有序相具有鲁棒性。通过利用角度分辨光电子能谱对自旋和轨道角动量的敏感性，该研究揭示了拓扑Kagome金属的自旋Berry曲率，并有助于确定其光谱指纹。
据介绍，Kagome材料作为一种展示不同对称性和拓扑性的新兴电子现象的基底材料备受关注。关于最近发现的XV6Sn6 Kagome家族（其中X是稀土元素）是否具有由自旋-轨道耦合引起的拓扑非平凡基态存在争议。这些非平凡基态将表现出有限的自旋Berry曲率和拓扑表面态。
附：英文原文
Title: Flat band separation and robust spin Berry curvature in bilayer kagome metals
Author: Di Sante, Domenico, Bigi, Chiara, Eck, Philipp, Enzner, Stefan, Consiglio, Armando, Pokharel, Ganesh, Carrara, Pietro, Orgiani, Pasquale, Polewczyk, Vincent, Fujii, Jun, King, Phil D. C., Vobornik, Ivana, Rossi, Giorgio, Zeljkovic, Ilija, Wilson, Stephen D., Thomale, Ronny, Sangiovanni, Giorgio, Panaccione, Giancarlo, Mazzola, Federico
Issue&Volume: 2023-05-18
Abstract: Kagome materials have emerged as a setting for emergent electronic phenomena that encompass different aspects of symmetry and topology. It is debated whether the XV6Sn6 kagome family (where X is a rare-earth element), a recently discovered family of bilayer kagome metals, hosts a topologically non-trivial ground state resulting from the opening of spin–orbit coupling gaps. These states would carry a finite spin Berry curvature, and topological surface states. Here we investigate the spin and electronic structure of the XV6Sn6 kagome family. We obtain evidence for a finite spin Berry curvature contribution at the centre of the Brillouin zone, where the nearly flat band detaches from the dispersing Dirac band because of spin–orbit coupling. In addition, the spin Berry curvature is further investigated in the charge density wave regime of ScV6Sn6 and it is found to be robust against the onset of the temperature-driven ordered phase. Utilizing the sensitivity of angle-resolved photoemission spectroscopy to the spin and orbital angular momentum, our work unveils the spin Berry curvature of topological kagome metals and helps to define its spectroscopic fingerprint.
DOI: 10.1038/s41567-023-02053-z
Source: https://www.nature.com/articles/s41567-023-02053-z