In this work the physical properties of the intermetallic compound TbRhIn 5 were investigated by means of temperature-dependent magnetic susceptibility, electrical resistivity, heat-capacity, and resonant x-ray magnetic diffraction experiments. TbRhIn 5 is an intermetallic compound that orders antiferromagnetically at T N = 45.5 K, the highest ordering temperature among the existing RRhIn 5 ͑1-1-5, R = rare earth͒ materials, which in contrast to what is expected from a de Gennes scaling along the RRhIn 5 series. The x-ray resonant diffraction data have allowed us to solve the magnetic structure of TbRhIn 5 . Below T N , we found a commensurate antiferromagnetic structure with a propagation vector ͑1/2,0,1/2͒ and the Tb moments oriented along the c axis. Strong ͑over two orders of magnitude͒ dipolar enhancements of the magnetic Bragg peaks were observed at both Tb absorption edges L II and L III , indicating a fairly high polarization of the Tb 5d levels. Using a mean-field model including an isotropic first-neighbor exchange interaction ͑J R-R ͒ and the tetragonal crystalline electrical field ͑CEF͒, we evaluate the influence of the CEF effects in the physical properties of TbRhIn 5 . The results reported here seem to corroborate a general trend of CEF-driven effects on T N along the RRhIn 5 series.

The Fe K x-ray absorption near edge structure of BaFe(2-x)Co(x)As(2) superconductors was investigated. No appreciable alteration in shape or energy position of this edge was observed with Co substitution. This result provides experimental support to previous ab initio calculations in which the extra Co electron is concentrated at the substitute site and do not change the electronic occupation of the Fe ions. Superconductivity may emerge due to bonding modifications induced by the substitute atom that weakens the spin-density-wave ground state by reducing the Fe local moments and/or increasing the elastic energy penalty of the accompanying orthorhombic distortion.

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The effects of K and Co substitutions and quasi-hydrostatic applied pressure (P < 9 GPa) in the local atomic structure of BaFe2As2, Ba(Fe0.937Co0.063)2As2 and Ba0.85K0.15Fe2As2 superconductors were investigated by extended x-ray absorption fine structure (EXAFS) measurements in the As K absorption edge. The As-Fe bond length is found to be slightly reduced ( 0.01Å) by both Co and K substitutions, without any observable increment in the corresponding Debye Waller factor. Also, this bond is shown to be compressible (κ = 3.3(3) × 10 −3 GPa −1 ). The observed contractions of As-Fe bond under pressure and chemical substitutions are likely related with a reduction of the local Fe magnetic moments, and should be an important tuning parameter in the phase diagrams of the Fe-based superconductors.