We have discovered that the layered nickelate Pr4Ni3O8 is metallic, with Ni 3d states of x2-y2 character that are hybridized with oxygen ligands.
Significance and Impact
Our result means that Pr4Ni3O8 corresponds to the overdoped, metallic régime of the cuprates, and suggests electron doping as a route to a nickelate superconductor.
- X-ray absorption spectroscopy (XAS) establishes strong x2-y2 Ni 3d-orbital polarization in bulk single crystals of R4Ni3O8 (R=La, Pr).
- DFT calculations corroborate XAS measurements to establish that Ni adopts a low-spin state with strong Ni 3d — O 2p hybridization.
- While the related La4Ni3O8 is a charge-ordered insulator, both transport and heat capacity data reveal that Pr4Ni3O8 is metallic, a necessary condition for potential cuprate-like superconductivity.
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