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Title: Control of magnetic, nonmagnetic, and superconducting states in annealed Ca(Fe1–xCox)₂As₂

We have grown single-crystal samples of Co substituted CaFe₂As₂ using an FeAs flux and systematically studied the effects of annealing/quenching temperature on the physical properties of these samples. Whereas the as-grown samples (quenched from 960°C) all enter the collapsed tetragonal phase upon cooling, annealing/quenching temperatures between 350 and 800°C can be used to tune the system to low-temperature antiferromagnetic/orthorhomic or superconducting states as well. The progression of the transition temperature versus annealing/quenching temperature (T-Tanneal) phase diagrams with increasing Co concentration shows that, by substituting Co, the antiferromagnetic/orthorhombic and the collapsed tetragonal phase lines are separated and bulk superconductivity is revealed. We established a 3D phase diagram with Co concentration and annealing/quenching temperature as two independent control parameters. At ambient pressure, for modest x and Tanneal values, the Ca(Fe₁₋xCox)₂As₂ system offers ready access to the salient low-temperature states associated with Fe-based superconductors: antiferromagnetic/orthorhombic, superconducting, and nonmagnetic/collapsed tetragonal.
Authors:
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Publication Date:
OSTI Identifier:
1103631
Type:
Publisher's Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 85; Journal Issue: 22; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English