Abstract
The novel field-induced single-molecule magnet based on a tetracoordinate mononuclear heteroleptic Co(II) complex involving two heterocyclic benzimidazole (bzi) and two thiocyanido ligands, [Co(bzi)2(NSC)2], (CoL4), was prepared and thoroughly characterized. The analysis of AC susceptibility data resulted in the spin reversal energy barrier U = 14.7 cm−1, which is in good agreement with theoretical prediction, Utheor. = 20.2 cm−1, based on axial zero-field splitting parameter D = −10.1 cm−1 fitted from DC magnetic data. Furthermore, mutual interactions between CoL4 and ferromagnetic barium ferrite BaFe12O19 (BaFeO) in hybrid materials resulted in suppressing of slow relaxation of magnetization in CoL4 for 1:2, 1:1 and 2:1 mass ratios of CoL4 and BaFeO despite the lack of strong magnetic interactions between two magnetic phases.
Highlights
CoL4 and ferromagnetic barium ferrite BaFe12O19 (BaFeO) in hybrid materials resulted in suppressing of slow relaxation of magnetization in CoL4 for 1:2, 1:1 and 2:1 mass ratios of CoL4 and BaFeO despite the lack of strong magnetic interactions between two magnetic phases
The research interest was accentuated by the ability of such complexes to serve as good models of local magnetic behavior on centers in polynuclear complexes, which were subject of magneto-chemical interest initially. This was due to the phenomenon of a slow-relaxation of magnetization (SRM) which allows individual complex molecules to behave as molecular nanomagnets, so called single –molecule magnets (SMMs) and this was discovered on polynuclear species firstly[2]
Such behavior can be observed due to an existence of energy barrier acting against thermally induced spin reversal and the height of energy barrier is defined as U = |D|(S2 – 1/4), where S is the half-integer spin of the metal center ground state and D is the axial parameter of zero-field splitting (ZFS), while the negative value of D parameter assures generation of the aforementioned barrier
Summary
CoL4 and ferromagnetic barium ferrite BaFe12O19 (BaFeO) in hybrid materials resulted in suppressing of slow relaxation of magnetization in CoL4 for 1:2, 1:1 and 2:1 mass ratios of CoL4 and BaFeO despite the lack of strong magnetic interactions between two magnetic phases. The research interest was accentuated by the ability of such complexes to serve as good models of local magnetic behavior on centers in polynuclear complexes, which were subject of magneto-chemical interest initially This was due to the phenomenon of a slow-relaxation of magnetization (SRM) which allows individual complex molecules to behave as molecular nanomagnets, so called single –molecule magnets (SMMs) and this was discovered on polynuclear species firstly[2]. Inspired by our recent research involving a study of interactions between molecule-based metamagnet {[Ni(en)2]3[Fe(CN)6]2⋅ 3H2O}n11 and nanocrystalline magnetite Fe3O4 resulting in magnetic superstructure[12], we decided to investigate the impact of ferromagnetic barium ferrite BaFe12O19 (BaFeO) upon reported static and dynamic magnetic properties of a single-ion molecule magnet CoL4. The heterogeneous solid state mixtures of CoL4 and BaFeO in mass ratios 1:2, 1:1 and 2:1, respectively, were prepared by ball milling and characterized by DC magnetization and AC susceptibility measurements with the aim to answer remarkable questions regarding the possibility of dipolar/exchange magnetic interactions between two magnetic components and possible influence of ferromagnetic component on SRM of CoL4
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