The formation of nano-layered grains and their enhanced superconducting transition temperature in Mg-doped FeSe0.9 bulks

Abstract

To search a proper dopant to further improve superconductivity in 11 type Fe-based superconductors makes sense to both their superconductivity mechanism and possible technological applications. In present work, Mg doped FeSe polycrystalline bulks were obtained by a two-step solid-state reaction method. Even though there are many MgSe and iron impurities existing in the Mg heavy doped FeSe bulks, they exhibit obviously increased Tc compared to undoped FeSe sample. It was found that Mg addition has little effect on the crystal lattice parameters of superconducting β-FeSe, whereas leads to the formation of nano-layered grain structure consisted of MgSe and β-FeSe with similar X-ray diffraction characteristics. Lots of nano-structural interfaces between FeSe and MgSe formed in this homogenous layered grain structure have significant effect on the superconducting properties and are responsible for the enhancement of Tc, as like the case of FeSe thin film on some specific substrates. Our work not only demonstrates a powerful way for raising Tc in bulk superconductors, but also provides a well-defined platform for systematic studies of the mechanism of unconventional superconductivity by considering interface effect.

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

“…The estimation of the optical bandgap of the rods by means of diffuse reflectance measurements of films indicates an optical bandgap of 3.2 eV, consistent with the literature values for ZnO 10 . The analysis of the films using X-ray photoelectron spectroscopy (XPS) is characterized by Zn 2p 1 / 2 and Zn 2p 3 / 2 core level peaks spectra at 1,045 and 1,022 eV, respectively, consistent with those observed previously for ZnO 11 12 .…”

Interface enhanced superconductivity in monolayer FeSe films on MgO(001): charge transfer with atomic substitution

“…Currently, we cannot exclude that Mg atoms may diffuse into FeSe monolayer. But it is worth noting that the T onset $ 18 K we observed here is higher than the T onset $ 12 K of optimal Mg-doped bulk FeSe [43].…”

High Pinning Force Values of a Fe(Se, Te) Single Crystal Presenting a Second Magnetization Peak Phenomenon

“…Despite their low T c values, it has been demonstrated that the IBSs can be suitable for magnet and wire production and/or highpower applications and high-current transport thanks to their high values of critical current density J c , irreversibility field and upper critical field [11][12][13][14][15][16] as well as their good inter-grain connectivity [8,13,17,18]. Among the various IBS families, the 11 family has attracted a lot of interest due to its very simple crystalline structure and to the possibility of easily doping it with several elements of the periodic table [19][20][21][22][23] in order to improve the superconducting properties of the compounds. Among the compounds of the 11 family, Fe(Se, Te) is one of the most studied compounds in recent years due to its relatively high T c (for single crystals between 12 K and 14.5 K), its chemical stability and also because it does not present poisonous elements in its stoichiometry.…”