Candidate High-T_c Superconductors in a Class of Quaternary Hydrides

Based on our previous work on Lu-H-N ternary hydride structures [arXiv:2305.18196], we propose a class of quaternary structures as potential very high temperature superconductors. In these structures, metallic hydrogen states are dominant at the Fermi energy (E_F) near ambient pressure by chemically preserving a core MH₁₁ (e.g., M=Lu). The computed electronic structure for different compositions within this class also exhibit hydrogen-dominant states near E_F. The networking-value critical temperature (T_c) estimator predicts all of these compounds have T_c around or above 200 K, with some compounds plausibly being room temperature superconductors near ambient pressures. We explore the stability and electronic properties of the structures in terms of local chemical bonding interactions, which give rise to metallic hydrogen sublattices common to very high T_c hydride superconductors. This is naturally realized in the proposed parent structure, which can be viewed as a semiconductor-metal-semiconductor heterostructure. These theoretically predicted structures can provide templates for the continued search for superconductors at ambient conditions.