Year: 2021
Type: article
Abstract: Finding large orbital polarization in Ni-based oxides has become a topic of paramount interest in recent years due to the prospect of finding superconductivity. In this work, we investigate the electronic structure of single-crystalline samples of ${\mathrm{Sr}}_{2}{\mathrm{CuO}}_{3}$ and Ni-doped ${\mathrm{Sr}}_{2}{\mathrm{CuO}}_{3}$ containing $\mathrm{Cu}/{\mathrm{NiO}}_{4}$ square planar units. Our polarization-dependent x-ray absorption spectroscopy experiments reveal extremely large orbital polarization $(\ensuremath{\sim}63%)$ for ${\mathrm{Ni}}^{2+}$. Cluster calculations and ab initio calculations find that the giant orbital polarization arises due to the low-spin $(S=0)$ configuration with two holes in the Ni $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbital, contrary to the expected high-spin $(S=1)$ state from Hund's first rule.
Language: Latvian
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: U.S. Department of Energy, Indian Institute of Science, Department of Science and Technology, Ministry of Science and Technology, India, Ministry of Education, India, Jawaharlal Nehru Centre for Advanced Scientific Research, Office of Science, Science and Engineering Research Board, Argonne National Laboratory
OpenAlex ID: W3083051819