Possible Superconductivity Transition in Nitrogen‐Doped Lutetium Hydride Observed at Megabar Pressure

Abstract The pursuit of room‐temperature superconductivity at an accessible synthetic pressure has been a long‐held dream for both theoretical and experimental physicists. Recently, a controversial report by Dasenbrock‐Gammon et al. claims that the nitrogen‐doped lutetium trihydride exhibits room‐temperature superconductivity at near‐ambient pressure. However, many researchers have failed to independently reproduce these results, which has sparked intense skepticism on this report. In this work, a LuH_2±xN_y sample is fabricated using high‐pressure and high‐temperature methods. The composition and structural characterization are the same as the aforementioned near‐ambient superconductor. In situ X‐ray diffraction investigations indicate that a high‐pressure phase transition toward Fmm‐LuH_3±xN_y occurred in the sample at 59 GPa. The temperature‐dependent resistance measurements reveal that two possible superconductivity transition are observed at 95 GPa, with T_c1 ≈6.5 K for high‐T_c phase and T_c2 ≈2.1 K for low‐T_c phase, arising from the disparate phases in the sample. Resistivity measurements in the Fmm‐LuH_3±xN_y phase under varying magnetic fields exhibited characteristics consistent with superconductivity, with an upper critical field μ₀H_c2(0) of 3.3 T measured at 163 GPa. This work is expected to shed some light on the controversy surrounding superconductivity in the nitrogen‐doped lutetium hydride system.