{
"id": "1909.04657",
"version": "v1",
"published": "2019-09-10T17:59:51.000Z",
"updated": "2019-09-10T17:59:51.000Z",
"title": "Electronic structures and topological properties in nickelates $Ln_{n+1}$Ni$_n$O$_{2n+2}$",
"authors": [
"Jiacheng Gao",
"Zhijun Wang",
"Chen Fang",
"Hongming Weng"
],
"comment": "10 pages, 7 figures, 4 tables",
"categories": [
"cond-mat.mtrl-sci",
"cond-mat.supr-con"
],
"abstract": "After the significant discovery of the hole-doped nickelate compound Nd$_{0.8}$Sr$_{0.2}$NiO$_2$, an analysis of the electronic structure, orbital components, Fermi surfaces, and band topology could be helpful to understand the mechanism of its superconductivity. Based on the first-principles calculations, we find that Ni $3d_{x^2-y^2}$ states contribute the largest Fermi surface. $Ln~5d_{3z^2-r^2}$ states form an electron pocket at $\\Gamma$, while $5d_ {xy}$ states form a relatively bigger pocket at A. These Fermi surfaces and symmetries can be reproduced by our two-band model, which consists of two elementary band representations: $B_{1g}@1a~\\oplus~A_{1g}@1b$. By hole doping, a hole pocket originating from Ni $3d_{xy}$ orbital can be introduced, which may be related to the observed sign change of Hall coefficient. We find that there is a band inversion happened at A, which can be affected by the value of Coulomb interaction $U$ in the calculations. With small $U$ and spin-orbital coupling, it gives rise to a pair of Dirac points along A-M. By introducing an additional Ni $3d_{xy}$ orbital, the hole-pocket band and the possible band inversion can be captured in the modified model. Besides, the nontrivial band topology in the ferromagnetic two-layer compound La$_3$Ni$_2$O$_6$ is discussed and the band inversion is associated with Ni $3d_{x^2-y^2}$ and La $5d_{xy}$ orbitals.",
"revisions": [
{
"version": "v1",
"updated": "2019-09-10T17:59:51.000Z"
}
],
"analyses": {
"keywords": [
"electronic structure",
"topological properties",
"band inversion",
"states form",
"ferromagnetic two-layer compound"
],
"note": {
"typesetting": "TeX",
"pages": 10,
"language": "en",
"license": "arXiv",
"status": "editable"
}
}
}