摘要
The iron-chalcogenide superconductor FeTe_(1-x)Se_(x) displays a variety of exotic features distinct from iron pnictides.Although much effort has been devoted to understanding the interplay between magnetism and superconductivity near x=0.5,the existence of a spin glass phase with short-range magnetic order in the doping range(x~0.1-0.3)has rarely been studied.Here,we use DC/AC magnetization and(quasi)elastic neutron scattering to confirm the spin-glass nature of the short-range magnetic order in a Fe_(1.07)Te_(0.8)Se_(0.2) sample.The AC-frequency dependent spin-freezing temperature T_(f) generates a frequency sensitivityΔT_(f)(ω)/[T_(f)(ω)Δlog_(10)ω]≈0.028 and the description of the critical slowing down withτ=τ0(T_(f)/T_(SG-1))^(-zv) gives T_(SG)≈22 K and zv≈10,comparable to that of a classical spin-glass system.We have also extended the frequency-dependent T_(f) to the smaller time scale using energy-resolution-dependent neutron diffraction measurements,in which the T_(N) of the short-range magnetic order increases systematically with increasing energy resolution.By removing the excess iron through annealing in oxygen,the spin-freezing behavior disappears,and bulk superconductivity is realized.Thus,the excess Fe is the driving force for the formation of the spin-glass phase detrimental to bulk superconductivity.
作者
田龙
刘盼盼
洪涛
Tilo Seydel
鲁兴业
罗会仟
李世亮
戴鹏程
Long Tian;Panpan Liu;Tao Hong;Tilo Seydel;Xingye Lu;Huiqian Luo;Shiliang Li;Pengcheng Dai(Center for Advanced Quantum Studies and Department of Physics,Beijing Normal University,Beijing 100875,China;Neutron Scattering Division,Oak Ridge National Laboratory,Oak Ridge,TN 37831,USA;Institut Max von Laue-Paul Langevin(ILL),71 Avenue des Martyrs,CS 20156,38042 Grenoble Cedex 9,France;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;Department of Physics and Astronomy,Rice University,Houston,TX 77005,USA)
基金
Beijing Normal University is supported by the National Natural Science Foundation of China (Grant Nos. 11734002 and 11922402, X.L.)
supported by the US Department of Energy (DOE),Basic Energy Sciences (BES),under Contract No. DE-SC0012311 (P.D.)