Сибирский федеральный университет

Тип публикации: статья из журнала

Год издания: 2015

Идентификатор DOI: 10.1016/j.jmmm.2015.05.006

Ключевые слова: Warwickites, Spin glass, Entanglement, Exchange interaction, Anisotropy, Cobalt, Cobalt compounds, Crystallography, Exchange interactions, Glass, Glass transition, Magnetic properties, Magnetic susceptibility, Magnetism, Magnetization, Nuclear magnetic resonance, Paramagnetism, Quantum entanglement, Single crystals, Specific heat, Competing interactions, Crystallographic sites, Curie-weiss paramagnetism, Entanglement witness, Spin-glass freezing, Uniaxial anisotropy

Аннотация: Magnetic properties of heterometallic warwickites MgFeBO4, Mg0.5Co0.5FeBO4, and CoFeBO4 are presented, highlighting the effect of Co substitution on the magnetic properties of these compounds. The analysis of magnetization and heat capacity data has shown that these compounds exhibit a spin-glass transition below T-SG = 10, 20 and 22 K. respectively. Using zero field ac susceptibility as entanglement witness we find that the low dimensional magnetic behavior above T-SG show quantum entanglement behavior chi(T)proportional to T-alpha(T) up to T-E approximate to 130 K. The alpha parameters have been deduced as a function of temperature and Co content, indicating the existence of random singlet phase in this temperature region. Above TE the paramagnetism is interpreted in terms of non-entangled spins giving rise to Curie-Weiss paramagnetism. The different intra- and inter-ribbon exchange interaction pathways have been calculated within a simple indirect coupling model. It is determined that the triangular motifs in the warwickite structure, together with the competing interactions, induce frustration. The spin-glass character is explained in terms of the substitutional disorder of the Mg, Fe and Co atoms at the two available crystallographic sites, and the frustration induced by the competing interactions. The Co substitution induces uniaxial anisotropy, increases the absolute magnetization and increases the spin-glass freezing temperature. The entanglement behavior is supported in the intermediate phase irrespective of the introduction of anisotropy by the Co substitution. (C) 2015 Elsevier B.V. All rights reserved.

Журнал: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

Выпуск журнала: Vol. 392

Номера страниц: 114-125

ISSN журнала: 03048853

Место издания: AMSTERDAM

Издатель: ELSEVIER SCIENCE BV

• Arauzo A. (Servicio de Medidas Fisicas, Universidad de Zaragoza)
• Frolov K.V. (Shubnikov Institute of Crystallography, RAS)
• Bartolome J. (Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza, Departamento de Fisica de la Materia Condensada)
• Kazak N.V. (L.V. Kirensky Institute of Physics, SB, RAS)
• Bayukov O.A. (L.V. Kirensky Institute of Physics, SB, RAS)
• Bezmaternykh L.N. (L.V. Kirensky Institute of Physics, SB, RAS)
• Ovchinnikov S.G. (Siberian State Aerospace University)
• Ivanova N.B. (Siberian Federal University)
• Knyazev Y.V. (Siberian Federal University)
• Platunov M.S. (Shubnikov Institute of Crystallography, RAS)
• Lyubutin I.S. (Shubnikov Institute of Crystallography, RAS)

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