High-Tc superconductivity up to 55 K under high pressure in the heavily electron doped Lix(NH3)yFe2Se2 single crystal

Abstract

We report a high-pressure study on the heavily electron doped Lix(NH3)yFe2Se2 single crystal by using the cubic anvil cell apparatus. The superconducting transition temperature Tc = 44 K at ambient pressure is first suppressed to below 20 K upon increasing pressure to Pc = 2 GPa, above which the pressure dependence of Tc(P) reverses and Tc increases steadily to ca. 55 K at 11 GPa. These results thus evidenced a pressure-induced second high-Tc superconducting (SC-II) phase in Lix(NH3)yFe2Se2 with the highest Tcmax = 55K among the FeSe-based bulk materials. Hall data confirm that in the emergent SC-II phase the dominant electron-type carrier density undergoes a fourfold enhancement and tracks the same trend as Tc(P). Interesting, we find a nearly parallel scaling behavior between Tc and the inverse Hall coefficient for the SC-II phases of both Lix(NH3)yFe2Se2 and (Li,Fe)OHFeSe. The present work demonstrates that high pressure offers a distinctive means to further raising the maximum Tc of heavily electron doped FeSe-based materials by increasing the effective charge carrier concentration via a plausible Fermi surface reconstruction at Pc.

14 pages, 4 figures

References in corpus (10)

• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Structure determination and coexistence of superconductivity and antiferromagnetic order in (Li0.8Fe0.2)OHFeSe
• Superconductivity at 32K and anisotropy in Tl0.58Rb0.42Fe1.72Se2 crystals
• Bipartite magnetic parent phases in the iron-oxypnictide superconductor
• Tuning phase transitions of FeSe thin flakes by field effect transistor with solid ion conductor as gate dielectric
• Phase diagram of (Li1-xFex)OHFeSe: a bridge between iron selenide and arsenide superconductors
• Superconductivity at Tc = 44 K in LixFe2Se2(NH3)y
• Effects of strain on the electronic structure, superconductivity, and nematicity in FeSe studied by angle-resolved photoemission spectroscopy
• Superconductivity across Lifshitz transition and anomalous insulating state in surface K-dosed (Li0.8Fe0.2OH)FeSe
• Extreme anisotropy and anomalous transport properties of heavily electron doped Lix(NH3)yFe2Se2 single crystals

Cited by in corpus (3)

• Heavily Hydride-ion-doped 1111-type Iron-based Superconductors: Synthesis, Physical Properties and Electronic Structure
• Stoichiometry and defect superstructures in epitaxial FeSe films on SrTiO3
• Importance of Fermi surface and magnetic interactions for the superconducting dome in electron doped FeSe intercalates