Absence of near-ambient superconductivity in N-doped lutetium hydride

[Submitted on 15 Mar 2023]

Abstract: Recently near-ambient superconductivity was claimed in N-doped lutetium
hydride [1]. This induces a worldwide fanaticism about the dream of room
temperature superconductivity under low pressures. By using a high pressure and
high temperature synthesis technique, we have successfully obtained the
nitrogen doped lutetium hydride (LuH$_{2pmtext{x}}$N$_y$) with a dark-bluish
color and a structure with the space group of $Fmbar{3}m$ evidenced by x-ray
diffraction. This structure is the same as that reported in Ref. [1]. The
energy dispersive X-ray spectroscopy (EDS) confirmed the existence of nitrogen
in some areas of the samples. At ambient pressure, we witness a kink of
resistivity and magnetization at about 300 K, which may correspond to a
rearrangement of hydrogen/nitrogen atoms, namely a structural transition.
However, by applying a pressure from 1 GPa to 6 GPa, we have seen a
progressively optimized metallic behavior without showing superconductivity
down to 10 K. Temperature dependence of magnetization shows a flat feature
between 100 and 320 K, and the magnetization increases with magnetic field at
100 K, all these are not expected for superconductivity at 100 K. Thus, we
conclude the absence of near-ambient superconductivity in this nitrogen-doped
lutetium hydride under pressures below 6 GPa.