Reddy B H, Ali Asif, Singh Ravi Shankar
Department of Physics, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal-462 066, India.
J Phys Condens Matter. 2021 Apr 23;33(18). doi: 10.1088/1361-648X/abf0c7.
We investigate the electronic structure of ternary palladatesPdO(= Sr, Ca) using valence band photoemission spectroscopy and band structure calculations. Energy positions of various features and overall width of the experimental valence band spectra are well captured by band structure calculations using hybrid functional. Band structure calculations within local density approximations lead to metallic ground state while the calculations using hybrid functional provide band gap of 0.25 eV and 0.22 eV for CaPdOand SrPdOrespectively, suggesting moderate to strong electron correlation strength in these narrow band gap semiconducting palladates. High resolution spectra reveal negligibly small intensity at Fermi level,, for parent compounds, while hole doped SrPdO(by 15% Li substitution at Sr site) exhibits a Fermi cut-off suggesting metallic character in contrast to semiconducting transport. These observations reveal the importance of localization of electrons in case where the Fermi edge falls in the mobility edge.
我们使用价带光电子能谱和能带结构计算研究了三元钯酸盐PdO（= Sr，Ca）的电子结构。使用杂化泛函的能带结构计算很好地捕捉了实验价带光谱的各种特征的能量位置和整体宽度。局域密度近似下的能带结构计算导致金属基态，而使用杂化泛函的计算分别为CaPdO和SrPdO提供了0.25 eV和0.22 eV的带隙，表明这些窄带隙半导体钯酸盐中存在中等至强的电子关联强度。高分辨率光谱显示，对于母体化合物，费米能级处的强度可忽略不计，而空穴掺杂的SrPdO（通过在Sr位点进行15%的Li替代）表现出费米截止，表明与半导体输运相反的金属特性。这些观察结果揭示了在费米边缘落在迁移率边缘的情况下电子局域化的重要性。
