Hidden kagome-lattice picture and origin of high conductivity in delafossite PtCoO2
Hidden kagome-lattice picture and origin of high conductivity in delafossite PtCoO2
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DOI：
10.1103/physrevmaterials.3.045002
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发表时间：
2018-12
影响因子：
3.4
通讯作者：
H. Usui;M. Ochi;Sota Kitamura;T. Oka;D. Ogura;H. Rosner;M. Haverkort;V. Sunko;P. King;A. Mackenzie;K. Kuroki
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文献类型：
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作者：
H. Usui;M. Ochi;Sota Kitamura;T. Oka;D. Ogura;H. Rosner;M. Haverkort;V. Sunko;P. King;A. Mackenzie;K. Kuroki
我们研究了delafote PtCoO$_2$的电子结构，以阐明其极小的电阻率和高迁移率。该能带在费米能级附近表现出陡峭的色散，尽管它主要是由典型局域化的Pt $d$轨道形成的。我们提出了一个基于两个隐藏的kagome-lattice-like电子结构的图：一个来自Pt $s+p_x/p_y$轨道，另一个来自Pt $d_{3z^2-r^2}+d_{xy}/d_{x^2-y^2}$轨道，每个轨道都位于三角晶格的键上。特别是，我们发现潜在的Pt $s+p_x/p_y$波段实际上决定了原始色散的陡峭度，因此，大的费米速度可以归因于Pt $s+p_x/p_y$波段的大宽度。更重要的是，类似kagome的电子结构在费米表面产生了“轨道动量锁定”，从而减少了杂质对电子的散射。我们得出结论，大的费米速度和轨道动量锁定可能是PtCoO$_2$中极小电阻率的原因。
We study the electronic structure of delafossite PtCoO$_2$ to elucidate its extremely small resistivity and high mobility. The band exhibits steep dispersion near the Fermi level despite the fact that it is formed mainly by Pt $d$ orbitals that are typically localized. We propose a picture based on two hidden kagome-lattice-like electronic structure: one originating from Pt $s+p_x/p_y$ orbitals, and the other from Pt $d_{3z^2-r^2}+d_{xy}/d_{x^2-y^2}$ orbitals, each placed on the bonds of the triangular lattice. In particular, we find that the underlying Pt $s+p_x/p_y$ bands actually determine the steepness of the original dispersion, so that the large Fermi velocity can be attributed to the large width of the Pt $s+p_x/p_y$ band. More importantly, the kagome-like electronic structure gives rise to "orbital-momentum locking" on the Fermi surface, which reduces the electron scattering by impurities. We conclude that the combination of the large Fermi velocity and the orbital-momentum locking is likely to be the origin of the extremely small resistivity in PtCoO$_2$.