Spin density wave rather than tetragonal structure is prerequisite for superconductivity in La<sub>3</sub>Ni<sub>2</sub>O<sub>7-δ</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41093825.
- Also identified by DOI 10.1038/s41467-025-63701-x and PMC identifier 12528665.
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Abstract
The pressure-induced high-temperature (T<sub>c</sub>) superconductivity in nickelates La<sub>3</sub>Ni<sub>2</sub>O<sub>7-δ</sub> has sparked significant interest to explore its superconductivity at ambient pressure. Whether the pressure-stabilized tetragonal structure is a prerequisite for achieving nickelate superconductivity at ambient pressure is under hot debate. Here, by post-annealing in high oxygen pressure environment, tetragonal La<sub>3</sub>Ni<sub>2</sub>O<sub>6.92</sub> single crystals are successfully obtained at ambient pressure, which exhibits a metallic behavior without a SDW transition. Moreover, superconductivity is also absent at high pressures up to ~ 70 GPa. Furthermore, by utilizing Helium as the pressure medium, we found that the superconductivity in pressurized orthorhombic La<sub>3</sub>Ni<sub>2</sub>O<sub>6.85</sub> is achieved in orthorhombic structure rather than tetragonal structure claimed previously. All these findings demonstrate that tetragonal structure is not prerequisite for achieving superconductivity in La<sub>3</sub>Ni<sub>2</sub>O<sub>7-δ</sub>. Finally, our present work suggests a deep correlation between SDW order and superconductivity, which imposes stringent constraints on the underlying mechanism for pressure-induced superconductivity in nickelates.