Is there a hydride superconducting above 77 K at ambient pressure
In plain words
Hydride superconductors need enormous pressure; the goal is a hydrogen-rich compound that keeps a high transition temperature, above liquid-nitrogen temperature, at normal pressure.
Precise statement
Determine whether any thermodynamically stable or long-lived metastable hydride has $T_c > 77\ \mathrm{K}$ at ambient pressure. An answer is a synthesized compound with zero resistance and diamagnetic shielding above 77 K at 1 bar, or a computational search with stated completeness showing none exists among a defined class.
What would settle it
Synthesis and characterization of a predicted candidate with resistive and magnetic transitions above 77 K at ambient pressure.
Status in the literature
Unverified note
Calculations (2024) predicted Mg2IrH6 with $T_{c}$ above $100\,\mathrm{K}$ at ambient pressure; no superconducting sample has been reported.