The study, mostly done by scientists from Max-Planck-Institute for Solid State Research in Stuttgart, investigates the unconventional crystal structure of La₃Ni₂O₇, a high-pressure superconductor, using advanced microscopy and diffraction techniques. Crystals were grown using the optical floating zone technique with a ScIDre HKZ furnace under high oxygen pressure, which is crucial for achieving the unconventional structure. Superconductivity is observed above 8 GPa, with significant changes in transition temperature under pressure. The distinct stacking deviates from the typical Ruddlesden-Popper phases and may explain variations in superconducting properties across samples. Similar deviating stacking was also observed by the group of J. Mitchell from Argonne National Lab and published earlier this year. The findings suggest that the superconducting properties may arise from filamentary channels within the structure, emphasizing the need for further research to understand these mechanisms.

Unconventional Crystal Structure of the High-Pressure Superconductor La 3 Ni 2 O