Local disorder and structure relation induced by magnetic exchange interactions in A2(Mo1-yMny)2O7 pyrochlores

JOURNAL OF ALLOYS AND COMPOUNDS

卷:865

Article

Castellano, C.¹  Scavini, M.¹  Berti, G.²  Rubio-Marcos, F.^3,4  Lamura, G.⁵  Sanna, S.⁶  Salas-Colera, E.^7,8,9  Munoz-Noval, A.¹⁰  Cimberle, M. R.⁵  Demartin, F.¹ 

[1] Univ Milan, Dipartimento Chim, Via Golgi 19, I-20133 Milan, Italy

[2] Inst Natl Rech Sci, Ctr Energie Mat Telecommun, 1650 Blvd Lionel Boulet, Varennes, PQ J3X 1S2, Canada

[3] CSIC, Electroceram Dept, Inst Ceram & Vidrio, Kelsen 5, Madrid 28049, Spain

[4] Univ Antonio Nebrija, Escuela Politecn Super, Pirineos 55, Madrid 28040, Spain

[5] Univ Genoa, Dipartimento Fis, CNR Spin, Via Dodecaneso 33, I-16146 Genoa, Italy

[6] Univ Bologna, Dept Phys & Astron, I-40127 Bologna, Italy

[7] CSIC, Inst Ciencia Mat Madrid, ICMM, Sor Juana Ines de la Cruz 3, Madrid 28049, Spain

[8] Spanish CRG BM25 SpLine, ESRF 71, ESRF 71,Ave Martyrs CS 40220 FR, F-38043 Grenoble, France

[9] Univ Carlos III Madrid UC3M, Dept Fis, Av Univ 30, Madrid 28911, Spain

[10] Univ Complutense Madrid, Fac CC Fis, Dept Fis Mat, Pza Ciencias 1, Madrid 28040, Spain

关键词: Oxide materials;    Order-disorder effects;    Exchange and superexchange;    EXAFS;    X-ray diffraction;   

DOI  :  10.1016/j.jallcom.2021.158958

来源: Elsevier

【 摘 要 】

We present an extended X-ray absorption fine structure study at the Mo K-edge of A(2)(Mo1-yMny)(2)O-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(2)Mo(2)O(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 Ho-2(Mo1-yMny)(2)O-7 (y = 0.05 and 0.10) keep the spin-glass nature of the parent compositions with a strong distortion of the MoO(1)(6) octahedron and of the Mo - Ho and Mo - Mo second shell. On the other hand, two Gd-2(Mo1-yMny)(2)O-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. (C) 2021 Elsevier B.V. All rights reserved.

【 授权许可】

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