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 $(\sim 63\%)$ 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 $3d_{x^2-y^2}$ orbital, contrary to the expected high-spin $(S=1)$ state from Hund's first rule.

Close

PrevNext

View figure in article

• Impurities in superconductors
• Magnetic susceptibility
• Superconducting phase transition
• Complex oxides
• Cuprates
• High-temperature superconductors
• Single crystal materials
• Density functional calculations
• Methods in superconductivity
• X-ray absorption spectroscopy