%0 Journal Article
%A Castellano, C.
%A Scavini, M.
%A Berti, G.
%A Rubio Marcos, F.
%A Lamura, G.
%A Sanna, S
%A Salas Colera, E.
%A Muñoz Noval, Álvaro
%A Cimberle, M. R.
%A Demartin, F.
%T Local disorder and structure relation induced by magnetic exchange interactions in A_2(Mo_(1-y)Mn_y)_2O_7 pyrochlores
%D 2021
%@ 0925-8388
%U https://hdl.handle.net/20.500.14352/8092
%X 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.
%~