Dilution effects in spin 7/2 systems. The case of the antiferromagnet GdRhIn5

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:405

Article

Lora-Serrano, R.¹  Garcia, D. J.^2,3  Betancourth, D.^4,5  Amaral, R. P.¹  Camilo, N. S.¹  Estevez-Rams, E.⁶  Ortellado G Z, L. A.⁷  Pagliuso, P. G.⁸ 

[1] Univ Fed Uberlandia, Inst Fis, BR-38408100 Uberlandia, MG, Brazil

[2] Consejo Nacl Invest Cient & Tecn, San Carlos De Bariloche, Rio Negro, Argentina

[3] Ctr Atom Bariloche, San Carlos De Bariloche, Rio Negro, Argentina

[4] Ctr Atom Bariloche, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina

[5] Inst Balseiro UN Cuyo, RA-8400 San Carlos De Bariloche, Rio Negro, Argentina

[6] Univ Habana IMRE, Inst Ciencias & Tecnol Mat, Havana 10400, Cuba

[7] Univ Fed Uberlandia, Inst Quim, BR-38408100 Uberlandia, MG, Brazil

[8] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083970 Campinas, SP, Brazil

关键词: Antiferromagnetism;    Magnetic dilution;    Substitutional disorder;    Heisenberg model;   

DOI  :  10.1016/j.jmmm.2015.12.093

来源: Elsevier

【 摘 要 】

We report the structural and magnetic characterization of La-substituted Gd(1-x)LaxRhIn(5) (x < 0.50) anti ferromagnetic (AFM) compounds. The magnetic responses of pure GdRhIn5 are well described by a S=7/ 2 Heisenberg model. When Gd3+ ions are substituted by Lai-', the maximum of the susceptibility and the inflection point of the magnetic specific heat are systematically shifted to lower temperatures accompanied by a broadening of the transition. The data is qualitatively explained by a phenomenological model which incorporates a distribution of magnetic regions with different transition temperatures (TN). The universal behaviour of the low temperature specific heat is found for La (vacancies) concentrations below x=0.40 which is consistent with spin wave excitations. For x=0.5 this universal behaviour is lost. The sharp second order transition of GdRhIn5 is destroyed, as seen in the specific heat data, contrary to what is expected for a Heisenberg model. The results are discussed in the context of the magnetic behaviour observed for the La -substituted (Ce,Tb,Nd)Rhln(5) compounds. (C) 2015 Elsevier B.V. All rights reserved.

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