• Journal of the Korean Magnetics Society
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• v.17 no.5
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• pp.215-220
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• 2007

The superexchange interaction is introduced to explain antiferromagnetic ordering in transition metal compounds such as MnO and $MnF_2$. The anisotropic superexchange (Dzyaloshinskii-Moriya: DM) interaction can be derived by incorporating the spin-orbit interaction into the superexchange interaction. The anisotropic superexchange DM can account for the weak ferromagnetism observed in transition metal compounds such as ${\alpha}-Fe_2O_3$, $MnCO_3$, $CrF_3$.

• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.173-178
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• 1993

We have calculated the reduced spontaneous magnetization in different environments and average value as func¬tion of reduced temperature of the magnetic ions(Fe) for A(tetrahedral) and B(octahedral) sites in spinel ferrites $AB_{2}O_{4}$ using A-O-B superexchange interaction. The reduced spontaneous magnetization and average value by A-O-B superexchange interaction are compared with that by A-B direct interaction. To contrast A-O-B superexchange interaction with A-B direct interaction, $M\"{o}ssbauer$ spectra from previous two interactions are obtained.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.467-471
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• 2011

Spin exchange interactions of $(C_2N_2H_{10})[Fe(HPO_3)F_3]$ were examined by performing a spin dimer analysis based on extended Huckel tight binding method and a mapping analysis based on first principles density functional theory. Spin exchange interactions occur through the super-superexchange paths $J_1$ and $J_2$ in $(C_2N_2H_{10})[Fe(HPO_3)F_3]$. In the super-superexchange path $J_2$ magnetic orbital interactions between eg-block levels are much stronger than those from $t_{2g}$-block levels. Both electronic structure calculations show that the spin exchange interaction through the super-superexchange path $J_2$ is much stronger than that of $J_1$.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.122-126
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• 2008

The magnetic properties of the organic/inorganic hybrid copper-methylenediphosphonate, Cu2(O3PCH2PO3) were examined by performing the spin dimer analysis based on the extended Hckel tight binding method. In Cu2(O3PCH2PO3) the CuO3 chains made up of edge-sharing CuO5 square pyramidal units are inter-linked by O-P-O bridges. The Cu-O-Cu superexchange interactions of the CuO3 chains are negligibly weak compared with the Cu-O…O-Cu super-superexchange interactions that occur between the CuO3 chains. The spin exchange interactions of Cu2(O3PCH2PO3) are dominated by three super-superexchange interactions, which leads to a three-dimensional antiferromagnetic spin lattice. The strongest spin exchange interactions form isolated spin dimers, which suggests that, to a first approximation, the magnetic properties can be described in terms of an isolated spin dimer model.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.52.1-52.1
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• 2007

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.239.1-239
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• 2003

• Bulletin of the Korean Chemical Society
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• v.26 no.12
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• pp.1965-1968
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• 2005

Extended H$\ddot{u}$ckel molecular calculations have been used to analyze how the magnitude of exchange coupling is influenced by the structural distortions in a series of dinuclear six-coordinate copper(II) complexes bridged by the planar bis-bidentate oxalate anion. Copper(II) ions have distorted octahedral surroundings, one being axially elongated and the other compressed. The magnetic interaction is strong in the former complexes and very weak in the latter. This is interpreted as resulting from a switching of magnetic spin orbitals due to the structural distortions (bond elongation or compression) of the copper sites.

• Proceedings of the Korean Magnestics Society Conference
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• 1999.04a
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• pp.106-107
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• 1999

• Journal of the Korean Magnetics Society
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• v.16 no.6
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• pp.287-292
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• 2006

Al substituted $CoAl_{0.5}Fe_{1.5}O_{4}$ has been studied with x-ray and neutron diffraction, $M\"{o}ssbauer$ spectroscopy and magnetization measurements. $CoAl_{0.5}Fe_{1.5}O_{4}$ revealed a cubic spinel structure of ferrinmagnetic long range ordering at room temperature, with magnetic moments of $Fe^{3+}(A)(-2.29{\mu}_{B}),\;Fe^{3+}(B)(3.81\;{\mu}_{B}),\;Co^{2+}(B)(2.66{\mu}_{B})$, respectively. The temperature dependence of the magnetic hyperfine field in $^{57}Fe$ nuclei at the tetrahedral (A) and octahedral (B) sites was analyzed based on the $N\'{e}el$ theory of magnetism. In the sample of $CoAl_{0.5}Fe_{1.5}O_{4}$, the interaction A-B interaction and intrasublattice A-A superexchange interaction were antiferromagnetic with strengths of $J_{A-B}=-19.3{\pm}0.2k_{B}\;and\;J_{A-A}=-21.6{\pm}0.2k_{B}$, respectively, while the intrasublattice B-B superexchange interaction was found to be ferromagnetic with a strength of $J_{B-B}=3.8{\pm}0.2k_{B}$.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1665-1668
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• 2010

The spin exchange interactions of $(VO)_2(H_2O){O_3P-(CH_2)_3-PO_3}{\cdot}2H_2O$ were examined by spin dimer analysis based on extended Huckel tight binding method. The strongest spin exchange interaction occurs through the super-superexchange path $J_2$ and the second strongest spin exchange interaction occurs through the superexchange interaction path $J_1$. There are two strongly interacting spin exchange paths in $(VO)_2(H_2O){O_3P-(CH_2)_3-PO_3}{\cdot}2H_2O$. Therefore, magnetic susceptibility curve of $(VO)_2(H_2O){O_3P-(CH_2)_3-PO_3}{\cdot}2H_2O$ can be well reproduced by an alternating onedimensional antiferromagnetic chain model rather than an isolated spin dimer model.