Structural evolution and phase diagram of the superconducting iron selenides Lix(C2H8N2)yFe2Se2(x=00.8)

Linlin Zhao, Da Wang, Qingzhen Huang, Hui Wu, Ruijin Sun, Xiao Fan, Yanpeng Song, Shifeng Jin, and Xiaolong Chen
Phys. Rev. B 99, 094503 – Published 4 March 2019
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Abstract

Here we report on the structural and electronic phase diagram of lithium and ethylenediamine intercalated FeSe in a wide range of dopant concentration (x=00.8). Undoped (C2H8N2)yFe2Se2 crystallizes in an orthorhombic phase. With increasing lithium doping, an orthorhombic to tetragonal phase transition occurs at x=0.35, and the superconducting tetragonal phase persists until x=0.5. Meanwhile, the Tc is found dependent strongly on dopant concentration, raising rapidly from 30 K at x=0.35 to 45 K at x=0.5. The crystal structures of Li0.31(3)(C2H8N2)0.52(7)Fe2.03(2)Se2 are determined by using high-resolution neutron diffraction data at 5, 60, 150, and 295 K, respectively. The distortion of the FeSe tetrahedron is enhanced significantly from 150 to 295 K, meanwhile, the normal-state Hall resistivity changes sign from negative to positive in the same temperature range. The dominant hole carrier in electron-doped Li0.5(C2H8N2)yFe2Se2 above 230 K suggests that the temperature-induced structure distortion may lead to a reconstruction of the Fermi surface topology and the appearance of hole pockets.

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  • Received 24 July 2018
  • Revised 13 January 2019

DOI:https://doi.org/10.1103/PhysRevB.99.094503

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Linlin Zhao1,2, Da Wang1, Qingzhen Huang3, Hui Wu3, Ruijin Sun1,2, Xiao Fan1,2, Yanpeng Song1,2, Shifeng Jin1,4,*, and Xiaolong Chen1,4,5,6,†

  • 1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 2University of Chinese Academy of Sciences, Beijing 100049, China
  • 3NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899, USA
  • 4School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 101408, China
  • 5Collaborative Innovation Center of Quantum Matter, Beijing, 100190, China
  • 6Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China

  • *Author to whom correspondence should be addressed: shifengjin@iphy.ac.cn
  • chenx29@iphy.ac.cn

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Issue

Vol. 99, Iss. 9 — 1 March 2019

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