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

resumo

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.

palavras-chave

INTERCALATION; AL

categoria

Chemistry; Materials Science; Mineralogy

autores

Pashkevich, YG; Fertman, EL; Fedorchenko, AV; Vieira, DEL; Neves, CS; Babkin, RY; Lyogenkaya, AA; Tarasenko, R; Tkác, V; Cizmár, E; Feher, A; Salak, AN

Grupos

G3 - Materiais Eletroquímicos, Interfaces e Revestimentos

Projectos

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

agradecimentos

This work was supported by the EU H2020 project European Microkelvin Platform (EMP) , grant agreement No. 824109. Yu. G. Pashkevich acknowledges the financial support of the Swiss National Science Foundation through the individual grant IZSEZ0_212006 of the ?Scholars at Risk? Program. D.E.L. Vieira acknowledges the financial support of FCT-Portugal through the individual PhD grant PD/BD/143033/2018. A.N. Salak and C.S. Neves acknowledge the financial support of national funds (OE) through FCT-Portugal in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree -Law 57/2016, of August 29, changed by Law 57/2017, of July 19. The research done in the University of Aveiro was supported by the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC) . The research at P.J. S ? af ? arik University was supported by the Slovak Research and Development Agency under grant No. APVV-18-0197 and by the Scientific Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Re- public under grant Nos. 1/0426/19 and 1/0512/23.