paper

Theoretical analysis on the possibility of superconductivity in a trilayer Ruddlesden-Popper nickelate LaNiO under pressure and its experimental examination: comparison with LaNiO

arXiv:2309.09462 · doi:10.1103/PhysRevB.109.144511

Abstract

We study the possibility of superconductivity in a trilayer Ruddlesden-Popper nickelate LaNiO under pressure both theoretically and experimentally, making comparison with the recently discovered high superconductor LaNiO, a bilayer nickelate. Through DFT calculations, we find that a structural phase transition from monoclinic to tetragonal takes place around 10 - 15 GPa. Using the tetragonal crystal structure, we theoretically investigate the possibility of superconductivity, where a combination of fluctuation exchange approximation and linearized Eliashberg equation is applied to a six-orbital model constructed from first principles band calculation. The obtained results suggests that LaNiO may also become superconducting under high pressure with comparable to some cuprates, although it is not as high as LaNiO. We also perform experimental studies using our polycrystalline samples of LaNiO and LaNiO. The superconducting transition of LaNiO, with a maximum onset of 67.0 K at a pressure of 26.5 GPa, is confirmed by a drop in the electrical resistance, as well as the magnetic field dependence of the resistance. Quite interestingly, similar temperature and magnetic field dependencies of the resistance are observed also for LaNiO, where a drop in the resistance is observed at lower temperatures compared to LaNiO, under pressures of 32.8 GPa and above. Given the theoretical expectation, the reduction in the resistance can most likely be attributed to the occurrence of superconductivity in LaNiO. The temperature at which the resistance deviates from a linear behavior, considered as the onset , monotonically increases up to 23 K at 79.2 GPa, which is opposite to the pressure dependence of in La3Ni2O7.01.

9 pages, 5 figures, Fig.4 added

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