Magnetic phenomena in Co-containing layered double hydroxides
Daniel E.L. Vieira1, Andrei N. Salak1, Alexey V. Fedorchenko2,3, Yurii G. Pashkevich3,4, Elena L. Fertman3, Vladimir A. Desnenko3, Roman Yu. Babkin4, Erik Čižmár2
Alexander Feher2, Augusto B. Lopes1, and Mário G.S. Ferreira1
1Department of Materials and Ceramic Engineering, CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal
2Institute of Physics, Faculty of Science, P.J. Šafárik University in Košice 9 Park Angelinum, Košice 04154, Slovakia
3B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Nauky Ave., Kharkiv 61103, Ukraine
4O. Galkin Donetsk Institute for Physics and Engineering of the National Academy of Sciences of Ukraine 46 Nauky Ave., Kyiv 03680, Ukraine
Received February 17, 2017
Magnetic behavior of CoII(n)AlIII layered double hydroxides (LDHs) (n = Co/Al = 2 and 3) intercalated withnitrate was studied as a function of temperature. Both LDH compounds are paramagnetic above about 8 K. A rapid increase of their magnetic moments occurs below this temperature until the moments reach the maximum values at Tmax of 4.0 K and 3.2 K for Co(2)Al–NO3 and Co(3)Al–NO3, respectively. Below Tmax, the zero-field-cooled and the field-cooled static magnetization curves are strongly different. Along with this low-temperature phenomena, Co(2)Al–NO3 and Co(3)Al–NO3 demonstrate anomalous behavior of their temperature dependence magnetic susceptibility in a higher-temperature range: between 75 and 175 K, both the paramagnetic Curie temperature and the effective magnetic moment change in a non-monotonous way. Possible structural reasons of the observed magnetic behavior of the CoII(n)AlIII LDHs are discussed.
PACS: 61.43.Gt Powders, porous materials; PACS: 75.50.Lk Spin glasses and other random magnets; PACS: 75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures).
Key words: layered structure, oxygen octahedra, static magnetization, effective magnetic moment.