Effect of hole doping on superconductivity in compressed CeH9 at high pressures

Abstract

The experimental realization of high-temperature superconductivity in compressed hydrides H3S and LaH10 under high pressures over 150 GPa has aroused great interest in reducing the stabilization pressure of superconducting hydrides. For cerium hydride CeH9 recently synthesized at 80–100 GPa, our first-principles calculations reveal that the strongly hybridized electronic states of Ce−4f and H−1s orbitals produce the topologically nontrivial Dirac nodal lines around the Fermi energy EF, which are protected by crystalline symmetries. By hole doping, EF shifts down toward the symmetry-driven van Hove singularity to increase the density of states, which in turn significantly raises a superconducting transition temperature Tc. We show that hole doping with Ce3+ ions can be very electronically miscible in CeH9 because both Ce3+ and Ce behave similarly as cations. Therefore, the interplay of crystalline symmetry, band topology, and hole doping contributes to enhance Tc in compressed CeH9, which can also be demonstrated in another superconducting rare-earth hydride, LaH10.

Source-reported materials — not catalogue approval

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