Diverse fluctuations and anisotropic Gr{\" u}neisen parameter behavior in iron-based superconductor Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ and their correlation with superconductivity

Abstract

In this study, the temperature dependence of elastic constants $C_{11}$, $C_{33}$, $C_{\mathrm{E}}=(C_{11}-C_{12})/2$, $C_{66}$ and $C_{44}$ of the iron-based superconductor Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ (0 $\leqq x\leqq$ 0.245) have been measured. This system shows a large elastic softening in $C_{66}$ towards low temperatures. In addition to $C_{66}$, which originates from orthorhombic structural fluctuation, the samples near the optimal concentration show remarkable structural fluctuation in $C_{11}$ and $C_{33}$ elastic modes, which correspond to ${\Gamma }_1$ (C4) symmetry. It suggests the existence of diverse fluctuations in this system. Gr{\" u}neisen parameters were analyzed under some assumptions for structural and magnetic transition temperatures. Results showed that the Gr{\" u}neisen parameters for the inter-plane strain are remarkably enhanced toward the QCP, while those for the in-plane stress tend to turn down near the QCP. Gr{\" u}neisen parameters for the superconducting transition are anisotropic and shows remarkable Co-concentration dependence, suggesting that the in-plane isotropic compression and inter-layer elongation enhance the superconductivity. The correlation of Gr{\" u}neisen parameters between $T_{\mathrm{S}}$, $T_{\mathrm{N}}$ and $T_{\mathrm{sc}}$ shows $c$-axis elongation and its relevant role in the emergence of superconductivity in this system.

19 pages and 10 figures

References in corpus (7)

• Superconductivity at 22 K in Co-doped BaFe2As2 Crystals
• Spin density wave anomaly at 140 K in the ternary iron arsenide BaFe2As2
• Magnetic order in BaFe2As2, the parent compound of the FeAs based superconductors in a new structural family
• Is LaO${}_{1-x}$F${}_x$FeAs an electron-phonon superconductor ?
• Phase transitions in LaFeAsO: structural, magnetic, elastic, and transport properties, heat capacity and Mossbauer spectra
• Pressure versus concentration tuning of the superconductivity in Ba(Fe(1-x)Cox)2As2
• Critical Slowing Down of Quadrupole and Hexadecapole Orderings in Iron Pnictide Superconductor

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• Giant Grüneisen parameter in a strain-tuned superconducting quantum paraelectric: A consequence of the vanishing ferroelectric phonon energy
• Nematic spin correlations pervading the phase diagram of FeSe${}_{1-x}$S${}_x$
• Possible signature of broken symmetry state near the quantum critical point in P doped BaFe${}_2$As${}_2$: A Raman spectroscopy study
• Nematic fluctuations mediated superconductivity revealed by anisotropic strain in Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$
• Quantitative relationship between structural orthorhombicity, shear modulus and heat capacity anomaly of the nematic transition in iron-based superconductors
• Elasto-Raman scattering: arsenic optical phonon as a probe of nematicity in BaFe${}_2$As${}_2$
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