Magnetic suppression for a possible Fe-poor organic-inorganic hybrid superconductor Fe14Se16(tepa)0.8(tepa=tetraethylenepentamine)with a superconducting transition at∼42 K  

作　　者：Da Li Qifeng Kuang Xiaoling Men Bo Zhang Jianqi Huang Xiaolei Shang Bing Yang Teng Yang Zhiwei Li Zhidong Zhang 

机构地区：[1]Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China [2]School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China [3]Key Lab for Magnetism and Magnetic Materials of the Ministry of Education,Key Lab for Special Functional Materials and Structure Design of the Ministry of Education,Lanzhou University,Lanzhou 730000,China

出　　处：《Journal of Materials Science & Technology》2024年第31期98-110,共13页材料科学技术(英文版)

基　　金：supported by the National Natural Science Foundation of China(Nos.52371203,51971221 and 52031014).

摘　　要：Composition/structure-dependent superconductivity for FeSe-based superconductors attracted great attention not only due to their high superconducting transition temperatures(TC),but also for understanding the origin of iron-based superconductivity.Here,we report a new Fe-poor organic-inorganic hybrid material Fe_(14)Se_(16)(tepa)0.8 with a paramagnetic-diamagnetic transition at∼42 K grown by a high-temperature organic-solution-phase method with soluble iron/selenium sources in a tepa solution,alternative to previous intercalation strategies.The Fe_(14)Se_(16)(tepa)0.8 phase is in a tetragonal layered hybrid structure with a nanoplate shape.Composition analyses reveal a Fe-poor characteristic of the hybrid in contrast to previous FeSe-intercalated superconductor,and selected area electron diffraction pattern is featured by Fe_(3)Se_(4) superstructures with a√2×√2 of Fe vacancy order.Ab initio density functional calculations show that minus Fe_(3)Se_(4) ions are stable in the hybrid and∼0.25e-/Fe_(0.75)Se is obviously larger than the reported values of approximately 0.2e-/FeSe in other FeSe-intercalated superconductors.Typical hysteresis loops and temperature dependence of dc/ac susceptibilities of the Fe_(14)Se_(16)(tepa)0.8 measured below∼42 K suggest a presence of the Meissner effect in this material.Effects of synthesis conditions on structures and magnetic properties of the hybrids show a magnetic evolution from a long-range ferrimagnetic(FIM)order of Fe_(14)Se_(16)(tepa)to a coexistence of FIM and superconducting(SC)orders of Fe_(14)Se_(16)(tepa)0.9 and an SC order of Fe_(14)Se_(16)(tepa)0.8.X-ray absorption spectrum(XAS)confirms the presence of ferric/ferrous irons.Mössbauer studies reveal that the high-TC superconductivity originates from a suppression of the FIM order through tuning the spin states of irons from high-spin Fe^(3+)(S=5/2)and Fe^(2+)(S=2)in the Fe_(14)Se_(16)(tepa)to low-spin Fe^(3+)(S=1/2)and Fe^(2+)(S=0)in the Fe_(14)Se_(16)(tepa)0.8.Although no zero resistance is detected even

关 键 词：Iron-based hybrid superconductor SUPERCONDUCTIVITY Superconducting transition Magnetic properties Solution synthesis 

分 类 号：O57[理学—粒子物理与原子核物理]