Frustration-driven spin freezing in the S=1/2 fcc perovskite Sr2MgReO6

DOI	Trouver le DOI : https://doi.org/10.1103/PhysRevB.68.134410
Auteur	Rechercher : Wiebe, C. R.; Rechercher : Greedan, J. E.; Rechercher : Kyriakou, P. P.; Rechercher : Luke, G. M.; Rechercher : Gardner, J. S.; Rechercher : Fukaya, A.; Rechercher : Gat-Malureanu, I. M.; Rechercher : Russo, P. L.; Rechercher : Savici, A. T.; Rechercher : Uemura, Y. J.
Format	Texte, Article
Résumé	The ordered perovskite Sr2MgReO6 of tetragonal symmetry [I4/m, a=5.5670(1)Å, c=7.9318(2)Å at T=295K] has been synthesized and characterized by x-ray and neutron diffraction, thermal gravimetric analysis dc susceptibility, heat capacity, and muon spin relaxation (μSR) experiments. The B site cations Re6+ and Mg2+ appear to be ordered due the large difference in formal charge. The Re6+ magnetic ions form a distorted fcc lattice of S=1/2 spins providing a frustrated topology of edge-shared tetrahedra. The material exhibits a weak magnetic glassiness shown by a cusp at ∼50 K in the dc susceptibility, a weak but broad heat capacity anomaly, and a low-temperature μSR line shape characteristic of a spin-glass state. A broad and strongly field- dependent maximum in the dc susceptibility suggests that magnetic correlations persist to ∼175 K, accompanied by a divergence in the field-cooled and zero-field-cooled susceptibility. The anisotropic nature of the superexchange pathways due to the tetragonal distortion is thought to disrupt the ideal frustrated environment and lead to weaker glassiness than Sr2CaReO6, which has TG∼14K, and a large specific heat anomaly. In contrast, Sr2MgReO6 has a small anomaly, and only about 3% of the entropy is released at TG∼50K, which is comparable to other unconventional spin glasses such as the jarosite (H3O)Fe3(SO4)2(OH)6(∼6%). TG∼50K is unusually high for this class of materials.
Date de publication	2003-10-07
Dans	Physical Review. B, Condensed Matter and Materials Physics 68, nº 13 (7 octobre 2003) : 134410–.
Langue	anglais
Publication du CNRC	Cette publication n’est pas du CNRC Ce sont des publications qui ont été rédigées par un auteur du CNRC, mais avant que celui-ci soit employé du CNRC.
Numéro NPARC	12334520
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Identificateur de l’enregistrement	346d981d-9663-4ee8-8c2b-f90793d864c6
Enregistrement créé	2009-09-10
Enregistrement modifié	2020-04-02

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