A Dynamical Approach to the Explanation of the Upper Critical Field Data of Compressed H₃S

Abstract

Excellent fits were obtained by Talantsev (MPLB 33, 1950195, 2019) to the temperature (T) - dependent upper critical field ( H c 2 ( T )) data of H 3 S reported by Mozaffari et al. [Nature Communications 10, 2522 (2019)] by employing four alternative phenomenological models, each of which invoked two or more properties from its sample-specific set S 1 = { T c , gap, coherence length, penetration depth, jump in sp.ht.} and a single value of the effective mass ( m* ) of an electron. Based on the premise that the variation of H c 2 ( T ) is due to the variation of the chemical potential μ ( T ) , we report here fits to the same data by employing a T- , μ- and m* -dependent equation for H c 2 ( T ) and three models of μ ( T ) , viz. the linear, the parabolic and the concave-upward model. For temperatures up to which the data are available, each of these provides a good fit. However, for lower values of T , their predictions differ. Notably, the predicted values of H c 2 (0) are much higher than in any of the models dealt with by Talantsev. In sum, we show here that the addressed data are explicable in a framework comprising the set S 2 = { μ , m* , interaction parameter λ m , Landau index N L }, which is altogether different from S 1 .