论文标题
基于钛基金属的电子词不含电荷密度波
Electronic nematicity without charge density waves in titanium-based kagome metal
论文作者
论文摘要
由Kagome网络上的过渡金属原子组成的分层结晶材料已成为研究异常电子现象的多功能平台。例如，在基于钒的Kagome超导体AV3SB5（在其中可以代表K，CS或RB）中，有一个父荷密度波相似乎同时打破了晶格的平移和旋转对称性。在这里，我们显示出一种对比的情况，可以在没有相应的电荷密度波的情况下进行电子列表 - 旋转对称而无需破坏转化对称性的旋转对称性。我们使用光谱图像扫描隧道显微镜研究Kagome Metal CSTI3BI5，该kagome金属CSTI3BI5是AV3SB5，但具有钛原子Kagome网络。 CSTI3BI5没有表现出任何可检测到的电荷密度波状态，但是与密度功能理论计算的比较揭示了低能量下的实质性电子相关效应。比较沿不同方向的散射波矢量的振幅，我们发现了一种电子各向异性，它破坏了晶格的六倍对称性，这是由面内和面外钛衍生的D轨道引起的。我们的工作揭示了电子轨道在CSTI3BI5中的作用，这表明在基于Fe的超导体中，列明键顺序的六边形类似物。
Layered crystalline materials that consist of transition metal atoms on a kagome network have emerged as a versatile platform to study unusual electronic phenomena. For example, in the vanadium-based kagome superconductors AV3Sb5 (where A can stand for K, Cs, or Rb) there is a parent charge density wave phase that appears to simultaneously break both the translational and the rotational symmetry of the lattice. Here, we show a contrasting situation where electronic nematic order - the breaking of rotational symmetry without the breaking of translational symmetry - can occur without a corresponding charge density wave. We use spectroscopic-imaging scanning tunneling microscopy to study the kagome metal CsTi3Bi5 that is isostructural to AV3Sb5 but with a titanium atom kagome network. CsTi3Bi5 does not exhibit any detectable charge density wave state, but comparison to density functional theory calculations reveals substantial electronic correlation effects at low energies. Comparing the amplitudes of scattering wave vectors along different directions, we discover an electronic anisotropy that breaks the six-fold symmetry of the lattice, arising from both in-plane and out-of-plane titanium-derived d orbitals. Our work uncovers the role of electronic orbitals in CsTi3Bi5, suggestive of a hexagonal analogue of the nematic bond order in Fe-based superconductors.
