Orbital textures and charge density waves in transition metal dichalcogenides
Orbital textures and charge density waves in transition metal dichalcogenides
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DOI：
10.1038/nphys3267
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发表时间：
2015-04-01
期刊：
影响因子：
19.6
通讯作者：
Geck, J.
中科院分区：
文献类型：
--
作者：
Ritschel, T.;Trinckauf, J.;Geck, J.
在层状材料中实现的低维电子系统往往会自发地破坏底层核晶格的对称性，形成所谓的密度波(1)；这种物质状态目前引起了极大的关注(2-6)。在这里，我们揭示了电荷密度波的一个显著而令人惊讶的特征，即它们与轨道有序的密切关系。对于原型材料1T-TaS_2，我们不仅证明了二维TaS_2层中的电荷密度波涉及到以前未知的极其复杂的轨道织构。我们还证明了轨道有序层的两个亚稳态堆积允许操纵电子结构的显著特征。事实上，这些轨道效应提供了一条将1T-TaS2纳米结构从金属转变为半导体的途径，具有大约200 meV的技术相关间隙。这种新型的轨道电子学对于正在进行的基于层状过渡金属二卤化物(7，8)的新型、小型化和超快器件的开发特别相关。
Low-dimensional electron systems, as realized in layered materials, often tend to spontaneously break the symmetry of the underlying nuclear lattice by forming so-called density waves(1); a state of matter that at present attracts enormous attention(2-6). Here we reveal a remarkable and surprising feature of charge density waves, namely their intimate relation to orbital order. For the prototypical material 1T-TaS2 we not only show that the charge density wave within the two-dimensional TaS2 layers involves previously unidentified orbital textures of great complexity. We also demonstrate that two metastable stackings of the orbitally ordered layers allow manipulation of salient features of the electronic structure. Indeed, these orbital effects provide a route to switch 1T-TaS2 nanostructures from metallic to semiconducting with technologically pertinent gaps of the order of 200meV. This new type of orbitronics is especially relevant for the ongoing development of novel, miniaturized and ultrafast devices based on layered transition metal dichalcogenides(7,8).