title: 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.
authors.affiliation: Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science &Engineering, Tianjin University, Tianjin 300072, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Lan
authors.affiliation: 1] Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science &Engineering, Tianjin University, Tianjin 300072, People's Republic of China [2] Institute for Superconducting and Electronic Materials, University of Wollongong, New South Wales, 2500, Australia.
authors.forename: Zongqing
authors.initials: Z
authors.lastname: Ma
authors.affiliation: Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science &Engineering, Tianjin University, Tianjin 300072, People's Republic of China.
authors.forename: Yongchang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science &Engineering, Tianjin University, Tianjin 300072, People's Republic of China.
authors.forename: Ning
authors.initials: N
authors.lastname: Chen
authors.affiliation: Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science &Engineering, Tianjin University, Tianjin 300072, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Cai
authors.affiliation: Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science &Engineering, Tianjin University, Tianjin 300072, People's Republic of China.
authors.forename: Huijun
authors.initials: H
authors.lastname: Li
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong, New South Wales, 2500, Australia.
authors.forename: Shaon
authors.initials: S
authors.lastname: Barua
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong, New South Wales, 2500, Australia.
authors.forename: Dipak
authors.initials: D
authors.lastname: Patel
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong, New South Wales, 2500, Australia.
authors.forename: M Shahriar
authors.initials: MS
authors.lastname: Al Hossain
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong, New South Wales, 2500, Australia.
authors.forename: Jung Ho
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong, New South Wales, 2500, Australia.
authors.forename: Shi Xue
authors.initials: SX
authors.lastname: Dou