Enhancing the three-dimensional electronic structure in 1111-type iron arsenide superconductors by H-substitution

Abstract

The 1111-type iron arsenide hydride CaFe1-xCoxAsH was synthesized by high-pressure solid-state reaction, and its electronic structure and superconducting properties were investigated. Bulk superconductivity was observed at x = 0.07-0.26. A maximum superconducting critical temperature Tcmax of 23 K was observed at x = 0.07. These values are in agreement with those of CaFe1-xCoxAsF. The calculated Fermi surface of CaFeAsH has a small three-dimensional 3D hole pocket around the Gamma point. This is a result of weak covalent bonding between the As 4p and H 1s orbitals. No such covalency exists in CaFeAsF, because the energy level of the F 2p orbital is sufficiently deep to inhibit overlap with the As 4p orbital. The similar superconducting properties of CaFe1-xCoxAsH and CaFe1-xCoxAsF are explained on the nesting scenario. The small 3D hole pocket of CaFe1-xCoxAsH does not significantly contribute to electron excitation. These findings encourage exploration of hydrogen-containing 1111-type iron-based materials with lower anisotropies and higher Tc applicable to superconducting wires and tapes.

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Cited by in corpus (7)

• Exploration of new superconductors and functional materials and fabrication of superconducting tapes and wires of iron pnictides
• High pressure growth and electron transport properties of superconducting SmFeAsO1-xHx single crystals
• Hydrogen-substituted superconductors SmFeAsO1-xHx misidentified as oxygen-deficient SmFeAsO1-x
• Role of Hydrogen in the Electronic Properties of CaFeAsH-based Superconductors
• High upper critical field (120 T) with small anisotropy of highly hydrogen-substituted SmFeAsO epitaxial film
• Inter- to Intra-Layer Resistivity Anisotropy of NdFeAs(O,H) with Various Hydrogen Concentrations
• Phase transition in CaFeAsH: bridging 1111 and 122 iron-based superconductors