Control of tetrahedral coordination and superconductivity in FeSe0.5Te0.5 thin films

Ab initio study of metastable occupation of tetrahedral sites in palladium hydrides and its impact on superconductivity

A recent experimental work on palladium hydrides suggested that metastable structures with hydrogen atoms occupying tetrahedral sites could lead to superconductivity above 50 K, a huge increase compared to the 10 K critical temperature of the stable structure with all hydrogen atoms occupying octahedral sites. By generating many structures with hydrogen atoms randomly occupying the octahedral and tetrahedral sites of the face-centered cubic lattice and calculating their energy at different theoretical levels from first principles, we determine that metastable structures with partial or full oc…

Superconductivity in Undoped BaFe2As2 by Tetrahedral Geometry Design

Fe-based superconductors exhibit a diverse interplay between charge, orbital, and magnetic ordering1-4. Variations in atomic geometry affect electron hopping between Fe atoms5,6 and the Fermi surface topology, influencing magnetic frustration and the pairing mechanism through changes of orbital overlap and occupancies7-11. Here, we experimentally demonstrate a systematic approach to realize superconductivity without chemical doping in BaFe2As2, employing geometric design within an epitaxial heterostructure. We control both tetragonality and orthorhombicity in BaFe2As2 through superlattice engi…

c轴堆叠调节的TaSe2多型体中的电荷密度波与超导性

Charge density wave and superconductivity modulated by c-axis stacking in the TaSe2 polytypes

TaSe2多型体中，c轴堆叠调控电荷密度波与超导性，通过不同堆叠方式影响层间耦合和电子结构。

Superconductivity in Ca10(Ir4As8)(Fe2As2)5 with Square-Planar Coordination of Iridium

We report the unprecedented square-planar coordination of iridium in the iron iridium arsenide Ca10(Ir4As8)(Fe2As2)5. This material experiences superconductivity at 16 K. X-ray photoemission spectroscopy and first- principles band calculation suggest Ir(II) oxidation state, which yields electrically conductive Ir4As8 layers. Such metallic spacer layers are thought to enhance the interlayer coupling of Fe2As2, in which superconductivity emerges, thus offering a way to control the superconducting transition temperature.

Local atomic configuration control of superconductivity in the undoped pnictide parent compound BaFe2As2

Emergent superconductivity is strongly correlated with the symmetry of local atomic configuration in the parent compounds of iron-based superconductors. While chemical doping or hydrostatic pressure can change the local geometry, these conventional approaches do not provide a clear pathway in tuning the detailed atomic arrangement predictably, due to the parent compounds complicated structural deformation in the presence of the tetragonal-to-orthorhombic phase transition. Here, we demonstrate a systematic approach to manipulate the local structural configurations in BaFe2As2 epitaxial thin fil…

通过衬底表面终止态揭示单层FeSe中的增强超导性

Unraveling Enhanced Superconductivity in Single-layer FeSe through Substrate Surface Terminations

本研究通过在含TiO2和SrO两种表面终止态的SrTiO3衬底上生长单层FeSe，结合多种表征与理论计算，明确最优电子关联是其超导转变温度提升的核心驱动因素。