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

Journal Article · · Physical Review B
 [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)

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.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE Office of Science (SC). Basic Energy Sciences (BES) (SC-22)
Grant/Contract Number:
AC52-06NA25396; FG02-01ER45927
OSTI ID:
1471306
Alternate ID(s):
OSTI ID: 1437075; OSTI ID: 1473670
Report Number(s):
LA-UR--18-28713
Journal Information:
Physical Review B, Journal Name: Physical Review B Journal Issue: 18 Vol. 97; ISSN 2469-9950; ISSN PRBMDO
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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Uniform Patterns of Fe-Vacancy Ordering in the K x (Fe,Co) 2– y Se 2 Superconductors journal October 2011
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Nanoscale phase separation of antiferromagnetic order and superconductivity in K0.75Fe1.75Se2 journal January 2012
Effective Doping and Suppression of Fermi Surface Reconstruction via Fe Vacancy Disorder in K x Fe 2 − y Se 2 journal October 2012
Electronic and magnetic phase diagram in KxFe2-ySe2 superconductors journal January 2012
Strong correlations between vacancy and magnetic ordering in superconducting K 0.8 Fe 2 − y Se 2 journal July 2016
Local structural disorder and superconductivity in K x Fe 2 − y Se 2 journal June 2012
Nodeless superconducting gap in AxFe2Se2 (A=K,Cs) revealed by angle-resolved photoemission spectroscopy journal February 2011
Nanoscale phase separation in the iron chalcogenide superconductor K 0 . 8 Fe 1 . 6 Se 2 as seen via scanning nanofocused x-ray diffraction journal August 2011
A Novel Large Moment Antiferromagnetic Order in K 0.8 Fe 1.6 Se 2 Superconductor journal August 2011
Superconductivity Tuned by the Iron Vacancy Order in K x Fe 2− y Se 2 journal February 2013
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Electronic nematicity above the structural and superconducting transition in BaFe2(As1−xP x )2 journal June 2012
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Common Crystalline and Magnetic Structure of Superconducting A 2 Fe 4 Se 5 ( A = K , Rb , Cs , Tl ) Single Crystals Measured Using Neutron Diffraction journal September 2011
KFe 2 Se 2 is the Parent Compound of K-Doped Iron Selenide Superconductors journal July 2012
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Cited By (3)

Correlated disorder-to-order crossover in the local structure of K x Fe 2 − y Se 2 − z S z journal September 2019
Multiple Electronic Components and Lifshitz Transitions by Oxygen Wires Formation in Layered Cuprates and Nickelates journal January 2019
Fermi-Bose Mixtures and BCS-BEC Crossover in High-Tc Superconductors journal June 2019

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