Magnetic order and lattice distortion in Rh- and Cu-doped BaFe$_{2}$As$_{2}$ single crystals

Recent investigations of superconducting Co-doped BaFe$_{2}$As$_{2}$ have highlighted the interplay between superconductivity, magnetism and structure. Here we report on the antiferromagnetic order, lattice distortion and their response to superconductivity in Rh-doped BaFe$_{2}$As$_{2}$ and compare the behavior with non-superconducting Cu-doped BaFe$_{2}$As$_{2}$ single crystals. Results of the neutron scattering experiment performed at HB1A, HFIR, Oak Ridge, are correlated with high-resolution x-ray diffraction, resistance and magnetization measurements. The magnetic and structural phase transitions are similarly suppressed by the different dopings and the temperature dependencies of the order parameters are comparable, whereas only the Rh-doped sample shows a reduction of the antiferromagnetically ordered Fe moment in the superconducting state as reported for the Co-doped series. -- The work at the Ames Laboratory was supported by the US DOE, office of science, under contract No. DE-AC02-07CH11358.