Fe-Vacancy-Ordered Fe4Se5: The Insulating Parent Phase of FeSe Superconductor
K. W. Yeh, Yan‐Ruei Chen, Tung-Sheng Lo, Phillip M. Wu, Ming-Jye Wang, Kuei‐Shu Chang‐Liao, Maw‐Kuen Wu
Abstract
We have carried out a detailed study to investigate the existence of an insulating parent phase for FeSe superconductor. The insulating Fe4Se5 with √5 × √5 Fe-vacancy order shows a 3D-Mott variable range hopping behavior with a Verwey-like electronic correlation at around 45 K. The application of the RTA process at 450 °C results in the destruction of Fe-vacancy order and induces more electron carriers by increasing the Fe3+ valence state. Superconductivity emerges with Tc ~ 8K without changing the chemical stoichiometry of the sample after the RTA process by resulting in the addition of extra carriers in favor of superconductivity.
Topics & Concepts
SuperconductivityCondensed matter physicsVacancy defectStoichiometryMaterials scienceVariable-range hoppingValence (chemistry)Phase (matter)ChemistryPhysicsPhysical chemistryThermal conductionComposite materialOrganic chemistryIron-based superconductors researchRare-earth and actinide compoundsCorporate Taxation and Avoidance