Unconventional Crystal Structure of the High-Pressure Superconductor La_{3}Ni_{2}O_{7}.

The discovery of high-temperature superconductivity in La_{3}Ni_{2}O_{7} at pressures above 14 GPa has spurred extensive research efforts. Yet, fundamental aspects of the superconducting phase, including the possibility of a filamentary character, are currently subjects of controversial debates. Conversely, a crystal structure with NiO_{6} octahedral bilayers stacked along the c-axis direction was consistently posited in initial studies on La_{3}Ni_{2}O_{7}.