Castellano, C.Scavini, M.Berti, G.Rubio Marcos, F.Lamura, G.Sanna, SSalas Colera, E.Muñoz Noval, ÁlvaroCimberle, M. R.Demartin, F.2023-06-172023-06-172021-06-050925-838810.1016/j.jallcom.2021.158958https://hdl.handle.net/20.500.14352/8092©2021 Elsevier Science We gratefully acknowledge the Spanish CRG at the ESRF for providing beamtime under experiment HC-3343. MS thanks Prof. Monica Dapiaggi for useful discussions. GL thanks Prof. Fabio M. Canepa for illuminating discussions. F.R.-M. gratefully acknowledge the support of the AEI (Spanish Government) Project (No. MAT2017-86450-C4-1-R). F.R.-M. is indebted to MINECO for the "Ramon y Cajal" contract (Ref: RyC-2015-18626), which is co-financed by the European Social Fund.We present an extended X-ray absorption fine structure study at the Mo K-edge of A_2(Mo_(1-y)Mn_y)_2O_7 (A = Gd, Ho; y = 0.05 and 0.10) pyrochlores, as a function of temperature and composition, coupled to diffractometric and magnetic characterizations. Extending the study reported in our previous paper on the pristine A_2Mo_2O_7 compounds to these Mo/Mn partially substituted samples, where we hypothesize a competition between double-exchange and superexchange couplings, we aim to check which structure parameters are related to the nature of the nearest-neighbor magnetic interactions, looking for the presence and evolution of order and structure anomalies. Two Ho samples A_2(Mo_(1-y)Mn_y)_2O_7 (y = 0.05 and 0.10) keep the spin-glass nature of the parent compositions with a strong distortion of the MoO octahedron and of the Mo - Ho and Mo - Mo second shell. On the other hand, two Gd_2(Mo_(1-y)Mn_y)_2O_7 samples, ferromagnetic at low temperature in the undoped case, show the appearance on a local scale of a spin-glass transition mirrored by a quite high structure disorder and by a distortion coherent with a lattice frustration after Mn-doping. Therefore, the Gd and Ho Mn-doped samples display a similar frustrated behavior, differently from the corresponding undoped ones.engAtribución-NoComercial-SinDerivadas 3.0 Españajournal articlehttp://dx.doi.org/10.1016/j.jallcom.2021.158958https://www.sciencedirect.com/open access538.9Oxide materialsOrder-disorder effectsExchange and superexchangeEXAFSX-ray diffractionFísica de materialesFísica del estado sólido2211 Física del Estado Sólido