Magnetic ordering in Co2+-containing layered double hydroxides via the low-temperature heat capacity and magnetisation study

• Autor(a) principal: Pashkevich, Yu.G.
• Data de Publicação: 2023
• Outros Autores: Fertman, E.L., Fedorchenko, A.V., Vieira, D. E. L., Neves, C. S., Babkin, R.Yu., Lyogenkaya, A.А., Tarasenko, R., Tkáč, V., Čižmár, E., Feher, A., Salak, A.N.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/36539
• topic: Layered double hydroxide; Heat capacity; Schottky-like anomaly; Magnetic ordering

The low-temperature heat capacity and the magnetisation of Co2+ n Al3+ layered double hydroxides (LDH) with the cobalt-to-aluminium ratio n = 2 and 3 and intercalated with different anions have been studied in a wide range of magnetic fields up to 50 kOe. The heat capacity, C(T), was found to demonstrate a Schottky-like anomaly observed as a broad local maximum in the temperature dependence below 10 K. The effect is caused by a splitting of the ground-state Kramers doublet of Co2+ in the internal exchange field and correlates with magnetic ordering in these LDH. In low applied fields, the temperature-dependent dc magnetic susceptibility demonstrates a pronounced rise, which is associated with an onset of magnetic ordering. Both the heat capacity anomaly and the magnetic susceptibility peak are more pronounced for the LDH with n = 2 than for those with n = 3. This feature is associated with an excess of the honeycomb-like Co–Al coordination (which corresponds to a 2:1 Co–Al ordering) over the statistical cation distribution in Co2Al LDH, while a rather random cobalt-aluminium distribution is typical for Co3Al LDH. The temperature of the Schottky-like anomaly measured in a zero field is independent of the interlayer distance. Application of the magnetic field results in a widening of the anomaly range and a shift to higher temperatures. The observed experimental data are typical for a cluster spin glass ground state.