The near-room-temperature upsurge of electrical resistivity in Lu-H-N is not superconductivity, but a metal-to-poor-conductor transition

The recent report of superconductivity in nitrogen-doped lutetium hydride (Lu-H-N) at 294 K and 1 GPa brought hope for long-sought-after ambient-condition superconductors. However, the failure of scientists worldwide to independently reproduce these results has cast intense skepticism on this exciting claim. In this work, using a reliable experimental protocol, we synthesized Lu-H-N while minimizing extrinsic influences and reproduced the sudden change in resistance near room temperature. With quantitative comparison of the temperature-dependent resistance between Lu-H-N and the pure lutetium before reaction, we were able to clarify that the drastic resistance change is most likely caused by a metal-to-poor-conductor transition rather than by superconductivity. Herein, we also briefly discuss other issues recently raised in relation to the Lu-H-N system.