CsFe4-δSe4: A Compound Closely Related to Alkali-Intercalated FeSe Superconductors

Kunkun Li; Qing-Zhen Huang; Qinghua Zhang; Zewen Xiao; Toshio Kamiya; Hideo Hosono; Duanduan Yuan; Jiangang Guo; Xiaolong Chen

doi:10.1021/acs.inorgchem.8b00179

CsFe_4-δSe₄: A Compound Closely Related to Alkali-Intercalated FeSe Superconductors

Inorg Chem. 2018 Apr 16;57(8):4502-4509. doi: 10.1021/acs.inorgchem.8b00179. Epub 2018 Mar 26.

Authors

Kunkun Li^{1

2}, Qing-Zhen Huang³, Qinghua Zhang¹, Zewen Xiao⁴, Toshio Kamiya^{4

5}, Hideo Hosono^{4

5}, Duanduan Yuan^{1

2}, Jiangang Guo¹, Xiaolong Chen^{1

6

7}

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , China.
² University of Chinese Academy of Sciences , Beijing 100049 , China.
³ NIST Center for Neutron Research , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States.
⁴ Materials Research Center for Element Strategy , Tokyo Institute of Technology , Yokohama 226-8503 , Japan.
⁵ Laboratory for Materials and Structures, Institute of Innovative Research , Tokyo Institute of Technology , Yokohama 226-8503 , Japan.
⁶ School of Physical Sciences , University of Chinese Academy of Sciences , Beijing 100049 , China.
⁷ Collaborative Innovation Center of Quantum Matter , Beijing 100084 , China.

PMID: 29578339
DOI: 10.1021/acs.inorgchem.8b00179

Abstract

We report the synthesis and characterizations of a new FeSe-based compound CsFe_4-δSe₄, which is closely related to alkali intercalated FeSe superconductors while exhibits distinct features. It does not undergo phase separation and antiferromagnetic transition. Powder neutron diffractions, electron microscopy and high-angle annular-dark-field images confirm that CsFe_4-δSe₄ possesses an ordered Cs arrangement as √2 × √2 superstructure, evidencing a B-centered orthorhombic lattice with a space group of Bmmm. The temperature-dependent powder neutron diffractions indicate no structural and magnetic transition from 320 to 5 K. In contrast to the symmetry-breaking in FeSe, this phase naturally possesses the orthorhombic symmetry even at room temperature. DFT calculations and transport measurements reveal a novel Fermi surface geometry with two electron-like sheets centered on Γ point and intermediate density of states at the Fermi level comparing with the value of FeSe and the superconducting A _xFe₂Se₂.