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Title: Fe-vacancy ordering in superconducting K 1–xFe 2–ySe 2: First-principles calculations and Monte Carlo simulations

Fe vacancies in the 33 K superconductor K 1–xFe 2–ySe 2 show ordering schemes that may be correlated with its superconducting properties. First-principles calculations and kinetic Monte Carlo simulations lead to a very simple model for vacancy ordering. Repulsive dipolar interactions between Fe vacancies show three ground states: a $$\sqrt{8}\times \sqrt{10}$$ rhombus-ordered structure for 12.5% vacancies, a $$\sqrt{5}\times \sqrt{5}$$ squared lattice for 20% vacancies, and a $$\sqrt{5}\times \sqrt{5}$$ rhombus-ordered structure for 25% vacancies. Other structural states are derived from these three ground states and may contain additional disordered spatial regions. As a result, the repulsive interaction between Fe vacancies arises from enhanced Fe–Se covalent bonds, which differs from the well-known attractive interaction of Fe vacancies in body-centered cubic Fe.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [3]
  1. Xi'an Jiaotong Univ., Xi'an (China)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Xi'an Jiaotong Univ., Xi'an (China); Univ. of Cambridge, Cambridge (United Kingdom)
Publication Date:
Report Number(s):
LA-UR-15-23116
Journal ID: ISSN 0953-2048
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Superconductor Science and Technology
Additional Journal Information:
Journal Volume: 28; Journal Issue: 9; Journal ID: ISSN 0953-2048
Publisher:
IOP Publishing
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; material science
OSTI Identifier:
1329680