A neutron scattering study of the interplay between structure and magnetism in Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$

Abstract

Single crystal neutron diffraction is used to investigate the magnetic and structural phase diagram of the electron doped superconductor Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$. Heat capacity and resistivity measurements have demonstrated that Co doping this system splits the combined antiferromagnetic and structural transition present in BaFe${}_2$As${}_2$ into two distinct transitions. For $x$=0.025, we find that the upper transition is between the high-temperature tetragonal and low-temperature orthorhombic structures with ($T_{\mathrm{TO}}=99\pm 0.5$ K) and the antiferromagnetic transition occurs at $T_{\mathrm{AF}}=93\pm 0.5$ K. We find that doping rapidly suppresses the antiferromagnetism, with antiferromagnetic order disappearing at $x\approx 0.055$. However, there is a region of co-existence of antiferromagnetism and superconductivity. The effect of the antiferromagnetic transition can be seen in the temperature dependence of the structural Bragg peaks from both neutron scattering and x-ray diffraction. We infer from this that there is strong coupling between the antiferromagnetism and the crystal lattice.

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Cited by in corpus (3)

• Homogeneous vs. inhomogeneous coexistence of magnetic order and superconductivity probed by NMR in Co and K doped iron pnictides
• Evolution of the bulk properties, structure, magnetic order, and superconductivity with Ni doping in CaFe2-xNixAs2
• The Electronic Phase Diagram of the Iron-based High Tc Superconductor Ba(Fe(1-x)Co(x))2As2 Under Hydrostatic Pressure (0 < x <0.099)