Giant orbital polarization of Ni$^{2+}$ in square planar environment
| Autor: | Mandal, Prithwijit, Patel, Ranjan Kumar, Rout, Dibyata, Banerjee, Rajdeep, Bag, Rabindranath, Karmakar, Koushik, Narayan, Awadhesh, Freeland, John W., Singh, Surjeet, Middey, Srimanta |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 103, 060504 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.103.L060504 |
| Popis: | Understanding the electronic behavior of Ni$^{2+}$ in a square planar environment of oxygen is the key to unravel the origin of the recently discovered superconductivity in the hole doped nickelate Nd$_{0.8}$Sr$_{0.2}$NiO$_2$. To identify the major similarities/dissimilarities between nickelate and cuprate superconductivity, the study of the electronic structure of Ni$^{2+}$ and Cu$^{2+}$ in an identical square planar environment is essential. In order to address these questions, we investigate the electronic structure of Sr$_2$CuO$_3$ and Ni doped Sr$_2$CuO$_3$ single crystals containing (Cu/Ni)O$_4$ square planar units. Our polarization dependent X-ray absorption spectroscopy experiments for Ni in Sr$_2$Cu$_{0.9}$Ni$_{0.1}$O$_3$ have revealed very large orbital polarization, which is a characteristic feature of high $T_c$ cuprate. This arises due to the low spin $S$=0 configuration with two holes in Ni 3$d_{x^2-y^2}$ orbitals - in contrast to the expected high spin $S$=1 state from Hund's first rule. The presence of such $S$=0 Ni$^{2+}$ in hole doped nickelate would be analogous to the Zhang Rice singlet. However, the Mott Hubbard insulating nature of the NiO$_4$ unit would point towards a different electronic phase space of nickelates, compared to high $T_c$ cuprates. Comment: 4 Figures |
| Databáze: | arXiv |
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