Gatti G, Crepaldi A, Puppin M, Tancogne-Dejean N, Xian L, De Giovannini U, Roth S, Polishchuk S, Bugnon Ph, Magrez A, Berger H, Frassetto F, Poletto L, Moreschini L, Moser S, Bostwick A, Rotenberg Eli, Rubio A, Chergui M, Grioni M
Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Lausanne Centre for Ultrafast Science (LACUS), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Phys Rev Lett. 2020 Aug 14;125(7):076401. doi: 10.1103/PhysRevLett.125.076401.
In nodal-line semimetals, linearly dispersing states form Dirac loops in the reciprocal space with a high degree of electron-hole symmetry and a reduced density of states near the Fermi level. The result is reduced electronic screening and enhanced correlations between Dirac quasiparticles. Here we investigate the electronic structure of ZrSiSe, by combining time- and angle-resolved photoelectron spectroscopy with ab initio density functional theory (DFT) complemented by an extended Hubbard model (DFT+U+V) and by time-dependent DFT+U+V. We show that electronic correlations are reduced on an ultrashort timescale by optical excitation of high-energy electrons-hole pairs, which transiently screen the Coulomb interaction. Our findings demonstrate an all-optical method for engineering the band structure of a quantum material.
在节线半金属中，线性色散态在倒易空间中形成狄拉克环，具有高度的电子 - 空穴对称性，且费米能级附近的态密度降低。结果是电子屏蔽作用减弱，狄拉克准粒子之间的相关性增强。在此，我们通过将时间和角度分辨光电子能谱与从头算密度泛函理论（DFT）相结合，并辅以扩展哈伯德模型（DFT + U + V）以及含时DFT + U + V，来研究ZrSiSe的电子结构。我们表明，通过高能电子 - 空穴对的光激发，电子相关性在超短时间尺度上降低，这会瞬时屏蔽库仑相互作用。我们的研究结果展示了一种用于调控量子材料能带结构的全光学方法。
