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Title: Appearance of superconductivity at the vacancy order-disorder boundary in K x Fe 2 - y Se 2

In this work, the role of phase separation and the effect of Fe-vacancy ordering in the emergence of superconductivity in alkali metal doped iron selenides A xFe 2-ySe 2 (A = K, Rb, Cs) is explored. High energy x-ray diffraction and Monte Carlo simulation were used to investigate the crystal structure of quenched superconducting (SC) and as-grown nonsuperconducting (NSC) K xFe 2-ySe 2 single crystals. The coexistence of superlattice structures with the in-plane √2 × √2 K-vacancy ordering and the √5 × √5 Fe-vacancy ordering were observed in both the SC and NSC crystals alongside the I4/mmm Fe-vacancy-free phase. Moreover, in the SC crystals, an Fe-vacancy-disordered phase is additionally proposed to be present. Monte Carlo simulations suggest that it appears at the boundary between the I4/mmm vacancy-free phase and the I4/m vacancy-ordered phases (√5 × √5). Lastly, the vacancy-disordered phase is nonmagnetic and is most likely the host of superconductivity.
Authors:
 [1] ;  [1] ;  [2] ; ORCiD logo [3] ;  [1]
  1. Univ. of Virginia, Charlottesville, VA (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-18-28713
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
AC52-06NA25396; FG02-01ER45927; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 18; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC). Basic Energy Sciences (BES) (SC-22); USDOE; USDOE Office of Science - Office of Basic Energy Sciences - Scientific User Facilities Division
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE
OSTI Identifier:
1471306
Alternate Identifier(s):
OSTI ID: 1437075; OSTI ID: 1473670

Duan, Chunruo, Yang, Junjie, Ren, Yang, Thomas, Sean Michael, and Louca, Despina. Appearance of superconductivity at the vacancy order-disorder boundary in KxFe2-ySe2. United States: N. p., Web. doi:10.1103/PhysRevB.97.184502.
Duan, Chunruo, Yang, Junjie, Ren, Yang, Thomas, Sean Michael, & Louca, Despina. Appearance of superconductivity at the vacancy order-disorder boundary in KxFe2-ySe2. United States. doi:10.1103/PhysRevB.97.184502.
Duan, Chunruo, Yang, Junjie, Ren, Yang, Thomas, Sean Michael, and Louca, Despina. 2018. "Appearance of superconductivity at the vacancy order-disorder boundary in KxFe2-ySe2". United States. doi:10.1103/PhysRevB.97.184502.
@article{osti_1471306,
title = {Appearance of superconductivity at the vacancy order-disorder boundary in KxFe2-ySe2},
author = {Duan, Chunruo and Yang, Junjie and Ren, Yang and Thomas, Sean Michael and Louca, Despina},
abstractNote = {In this work, the role of phase separation and the effect of Fe-vacancy ordering in the emergence of superconductivity in alkali metal doped iron selenides AxFe2-ySe2 (A = K, Rb, Cs) is explored. High energy x-ray diffraction and Monte Carlo simulation were used to investigate the crystal structure of quenched superconducting (SC) and as-grown nonsuperconducting (NSC) KxFe2-ySe2 single crystals. The coexistence of superlattice structures with the in-plane √2 × √2 K-vacancy ordering and the √5 × √5 Fe-vacancy ordering were observed in both the SC and NSC crystals alongside the I4/mmm Fe-vacancy-free phase. Moreover, in the SC crystals, an Fe-vacancy-disordered phase is additionally proposed to be present. Monte Carlo simulations suggest that it appears at the boundary between the I4/mmm vacancy-free phase and the I4/m vacancy-ordered phases (√5 × √5). Lastly, the vacancy-disordered phase is nonmagnetic and is most likely the host of superconductivity.},
doi = {10.1103/PhysRevB.97.184502},
journal = {Physical Review B},
number = 18,
volume = 97,
place = {United States},
year = {2018},
month = {5}
}