Determining the upper critical magnetic field for N-doped lutetium hydride directly from the source data files in Dasenbrock-Gammon et al., Nature $\underline{615}$, 244 (2023)

Abstract

The Ginzburg-Landau-based upper critical magnetic field $H_{\textrm{C2}}$ (0) $\approx$ 88 T for N-doped lutetium hydride, reported in Dasenbrock-Gammon et al., Nature $\textbf{615}$, 244 (2023), is obtained therein by modeling resistance behavior, defining transitions widths, and applying magnetic fields $H$ = 1 T and 3 T. A method is presented herein for determining the critical temperature $T_{\textrm{C}}$ ($H$) directly from the resistance drops in the source data, implying a temperature slope -d$H_{\textrm{C2}}$ /d$T$ of 0.46(6) ${-}$ 0.51(5) T/K and, by applying pure BCS theory, an $H_{\textrm{C2}}$ (0) of 71(10) ${-}$ 79(8) T.