Importance of the crystal structure for superconductivity in infinite-layered nickel oxides

Abstract

We investigate the possibility of obtaining an infinite-layered superconducting nickel oxide using a topotactic reduction of R2−xSrxNiO4 nickelate compounds. We consider the case of reducing La0.8Sr1.2NiO4, which is metallic and with an effective Ni3.2+ valence into La0.8Sr1.2NiO3 with an effective Ni1.2+ valence similar to the original superconducting nickelate. Here we show that the reduction process is more likely to produce a NiO2 square striped structure instead of a layered structure, yielding an insulating state associated to a charge-ordered pattern of Ni+ and Ni2+ cations and antiferromagnetism. Although the appropriate valence for Ni cations is reached, it appears that both the crystal structure and the dimensionality of the system are critical for reaching superconductivity in these nickelates.

Source-reported materials — not catalogue approval

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