Floating zone growth at high oxygen pressures in Ruddlesden-Popper bilayer nickelate Y$_{y}$Sr$_{3-y}$Ni$_{2-x}$Al$_{x}$O$_{7-Î´}$

H. Yilmaz; P. Sosa-Lizama; M. Knauft; K. KÃ¼ster; U. Starke; M. Isobe; O. Clemens; P. A. van Aken; Y. E. Suyolcu; P. Puphal

doi:10.1038/s42005-025-02340-6

paper

Floating zone growth at high oxygen pressures in Ruddlesden-Popper bilayer nickelate Y $_{y}$ Sr $_{3 - y}$ Ni $_{2 - x}$ Al $_{x}$ O $_{7 - I^´}$

arXiv:2503.07861 · doi:10.1038/s42005-025-02340-6

Abstract

With the discovery of superconductivity under pressure in the Ruddlesden-Popper (RP) bilayer La $_{3}$ Ni $_{2}^{2.5 +}$ O $_{7}$ and trilayer La $_{4}$ Ni $_{3}^{2.66 +}$ O $_{10}$ , a new field of nickelate superconductors opened up. In this respect, Sr-Ni-O RP-type phases represent alternative systems that exist with partial cation substitution. We demonstrate that by Y-doping in Sr $_{3}$ Ni $_{2 - x}$ Al $_{x}$ O $_{7}$ (SNAO), as Y $_{y}$ Sr $_{3 - y}$ Ni $_{2 - x}$ Al $_{x}$ O $_{7}$ (YSNAO), the drawback of an insulating ground state is overcome, and a significant decrease in resistivity is achieved with crystals exhibiting semiconducting behavior. We employ optical floating zone (OFZ) growth at 10 bar oxygen partial pressure to explore the phase formation in a narrow region of Y-Sr-Ni-Al-O and investigate via DFT the general stability of the pure Sr-Ni-O scenario. Using extensive diffraction and spectroscopy, as well as transport and magnetization measurements, the structural, chemical, electrical, and magnetic properties of the as-grown and reduced compounds were investigated. The optimal growth of YSNAO allows for large high quality crystals suitable for neutron studies. In the Al-free growth, a known $n = 1$ RP system with Sr $_{1.66}$ Y $_{0.33}$ NiO $_{4 - I^´}$ , from which the first single crystals were obtained, was further confirmed, opening the door for future exploration of \textit{A}-site substituted RP-type phases without Ni-site disorder.

Floating zone growth at high oxygen pressures in Ruddlesden-Popper bilayer nickelate Yy​Sr3−y​Ni2−x​Alx​O7−I^´​

Abstract

Floating zone growth at high oxygen pressures in Ruddlesden-Popper bilayer nickelate Y $_{y}$ Sr $_{3 - y}$ Ni $_{2 - x}$ Al $_{x}$ O $_{7 - I^´}$