Absence of large nanoscale electronic inhomogeneities in the Ba(Fe1-xCox)2As2 pnictide

• Published in: The European physical journal. B, Condensed matter physics Vol. 73; no. 2; pp. 161 - 166
• Main Authors: Laplace, Y., Bobroff, J., Rullier-Albenque, F., Colson, D., Forget, A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 2010; EDP Sciences
• Subjects: Complex Systems; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Effects of crystal defects, doping and substitution; Exact sciences and technology; Fluid- and Aerodynamics; Magnetic properties; Physics; Physics and Astronomy; Properties of type I and type II superconductors; Solid State and Materials; Solid State Physics; Superconductivity; Transition temperature variations; Magnetic Transition; BaFe; Spin Density Wave; Doping Distribution; Nuclear Quadrupole Resonance; Line shape; Superconducting transitions; Doping; Line widths; Magnetic transitions; Pnictides; Nanometer scale; Chemical shift; Monocrystals; Superconductors; Anisotropy; Inhomogeneity; Cobalt additions; Nuclear magnetic resonance; Iron based arsenide; Barium Iron Arsenides Mixed
• ISSN: 1434-6028; 1434-6036
• DOI: 10.1140/epjb/e2009-00414-x

75 As NMR and susceptiblity were measured in a Ba(Fe 1-x Co x ) 2 As 2 single crystal for x = 6% for various field H values and orientations. The sharpness of the superconducting and magnetic transitions demonstrates a homogeneity of the Co doping x better than ±0.25%. On the nanometer scale, the paramagnetic part of the NMR spectra is found very anisotropic and very narrow for H∥ab which allows to rule out the interpretation of reference [J. Phys. Soc. Jpn 78 , 013711 (2009); Phys. Rev. B 79 , R 140506 (2009)] in terms of strong Co induced electronic inhomogeneities. We propose that a distribution of hyperfine couplings and chemical shifts due to the Co effect on its nearest As explains the observed linewidths and relaxations. All these measurements show that Co substitution induces a very homogeneous electronic doping in BaFe 2 As 2 , from nano to micrometer lengthscales, on the contrary to the K doping.