SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom.
Diamond Light Source, Harwell Campus, Didcot OX11 0DE, United Kingdom.
Phys Rev Lett. 2019 Feb 22;122(7):076404. doi: 10.1103/PhysRevLett.122.076404.
We revisit the enduring problem of the 2×2×2 charge density wave (CDW) order in TiSe_{2}, utilizing photon energy-dependent angle-resolved photoemission spectroscopy to probe the full three-dimensional high- and low-temperature electronic structure. Our measurements demonstrate how a mismatch of dimensionality between the 3D conduction bands and the quasi-2D valence bands in this system leads to a hybridization that is strongly k_{z} dependent. While such a momentum-selective coupling can provide the energy gain required to form the CDW, we show how additional "passenger" states remain, which couple only weakly to the CDW and thus dominate the low-energy physics in the ordered phase of TiSe_{2}.
我们重新研究了 TiSe_{2} 中 2×2×2 电荷密度波（CDW）序的持久问题，利用光子能量依赖的角分辨光电子能谱来探测全三维高温和低温电子结构。我们的测量结果表明，该体系中 3D 导带和准 2D 价带之间的维度不匹配如何导致强烈依赖于 k_{z} 的杂化。虽然这种动量选择耦合可以提供形成 CDW 所需的能量增益，但我们展示了如何留下额外的“乘客”态，它们仅与 CDW 弱耦合，因此主导 TiSe_{2}有序相中的低能物理。
