cyanide-bridged 3d-4f complexes of magnetic properties of molecular magnets

Title: cyanide-bridged 3d-4f complexes of magnetic properties of molecular magnetsAuthor: LinaDegree-granting unit: Guangxi Normal UniversityKeywords: cyanide-bridged complexes;; molecular magnets;; magnetic interactions;; rare earth - iron cyanideSummary:

Cyanide-bridged metal complexes because of its emergence over the Curie temperature and room temperature fascinating magnetic phenomena such as light, widespread in many areas of concern. However, such complexes are concentrated in the transition Neodymium Magnets metal ions, to the current complex of 3d-4f magnetic exchange interaction studies is still very small. Impact of such complexes as the main source of magnetic rare earth ions under the age of the 4f electrons of rare earth ions as Ln3 (except Gd3) has non-zero orbital angular momentum (L), spin-orbit coupling affects only the spin-isotropic The Hamiltonian of use. Crystal field and orbital contributions to the combined effects lead to the anisotropy of magnetic susceptibility and exchange interaction. In recent years, the use of DMF, and betaine synthesized a series of mixed ligand cyanide-bridged rare earth - transition metal polynuclear complexes. Found in 3d-4f cyanide-bridged complexes is rich and novel arrangement of the spatial structure of systems, and unique optical and magnetic properties, and has a special application potential as physics, chemistry and materials science an important issue of cross-disciplinary a paper by the complex combination of magnetic measurements and the microscopic molecular structure has been confirmed, the cyanide-bridged 3d-4f complexes for magnetic studies. The major findings of this paper are as follows:

1 Research of the weak magnetic field 100 Oe under the hybrid cyanide-bridged 3d-4f dinuclear complexes [Ln (H2O) 3 (DMF) 4 (μ-CN) Fe (CN) 5] · nH2O (Ln = Nd, Gd, Er) magnetic. At high temperatures, these three samples follow the Curie - Weiss law, by extrapolation χm-1 vs. T curve of the linear part to χm-1 = 0, get three samples of this paramagnetic Curie temperature θ <0, confirmed the existence of such complexes between the anti-spin magnetic interaction. One sample [GdFe] and [ErFe] the magnetic susceptibility at low temperatures follows the Curie - Weiss law. [NdFe] When the temperature is below 50K, the magnetic susceptibility deviates from the Curie - Weiss law, mainly due to low temperature when the Nd3 ground state and first excited state level populations change. Through the Hamiltonian H = JS1S2 β (S1g1 S2g2) H of such binuclear fitting Nd3, Gd3, Er3 spin interaction between the points and Fe3, respectively J-48.4cm-1,-0.44cm-1 ,-6.06cm-1, the J value and the size of the main rare earth ions Nd3, Gd3, Er3 non-linear magnetic structures that cyanide-bridged Ln and Fe ions exist between the antiferromagnetic spin interactions.

2 The main study of low field 10Oe, 100 Oe under cyanide-bridged 3d-4f dinuclear LnFe (CN) 6.4 H2O (Ln = Sm3, Gd3) magnetic. Samples [GdFe] by extrapolation χm-1 vs. T curve of the linear part of the χm-1 = 0, get three samples of this paramagnetic Curie temperature θ <0, these complexes were confirmed anti-magnetic. One sample [SmFe] the magnetic susceptibility does not follow the Curie-Weiss law, which is due to the ground state of Sm ions and the first excited state of the Zeeman effect of the distribution. But both χmT changes with temperature T have the same trend that can be explained by molecular field theory, in the compounds [LnFe], confirmed the Ln-Fe-spin interaction is antiferromagnetic behavior, as Sm3 / Gd3 has a large magnetic moment, and Sm3 / Gd3 the short distance between, but also that they have non-negligible ferromagnetic spin interactions. Ln-Fe at http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets low temperature spin-spin interaction slightly larger than the Gd-Gd interaction, and both belong to the same order of magnitude, these two types of interactions makes these compounds at low temperature was ferrimagnetic order.

Finally, a brief summary of this work, and looked to the future 3d-4f metal complexes study of molecular magnets.Degree Year: 2010