• Journal of the Korean Magnetics Society
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• v.25 no.6
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• pp.175-179
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• 2015

The half-metallicity and magnetism of the (001) surfaces of $(AlP)_1/(CrP)_1$ superlattice were investigated by means of FLAPW (Full-potential Liniarized Augmented Plane Wave) method. We considered four types of (001) surface termination, i.e., Al(S)-, Cr(S)-, P(S)Al(S-1)- and P(S)Cr(S-1)-term systems. We found that only Cr(S)-term system maintains the half-metallicity at the surface as only this system has the calculated magnetic moment of integer number of bohr magnetons. The magnetic moment of Cr(S) atom in the system was $3.02{\mu}_B$ which was increased from the bulk value by the effects of band narrowing and increased spin-splitting at the surface. The electronic density of states of the P(S) atom in the P(S)Al(S-1)-term showed very sharp surface states due to the broken $p_z$ bonds at the surface. We found there is still a strong p-d hybridization between the P(S) and Cr(S-1) layers in the P(S)Cr(S-1)-term which causes a considerable increase of magnetic moment of P(S) atom.

• Journal of the Korean Magnetics Society
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• v.19 no.6
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• pp.197-202
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• 2009

The property of soft magnetism for the Corning glass/non-buffer or buffer Ta/Conetic(NiFeCuMo)/Ta prepared by the ion beam deposition sputtering was studied. The effect of crystal property and post annealing treatment depending on the thickness of Conetic thin films was investigated. The coercivities of Conetic thin films with easy and hard direction along to the applying magnetic field during deposition were compared with each other. The coercivity and magnetic susceptibility of Ta(5 nm)/Conetic(50 nm) thin film were 0.12 Oe and 1.2 ${\times}\;10^4$, respectively. From these results, firstly, the Conetic thin film was more soft magnetism thin film than other one such as permalloy NiFe. Secondly, the usage of soft magnetism Conetic thin film for GMR-SV (giant magneoresistance-spin valve) or MTJ (Megnetic Tunnel Junction) structure in a low magnetic field can be possible.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.976-981
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• 1997

The magnetic susceptibilities of molybdenum ions with 4d1 electronic configuration in the octahedral crystal field were calculated on the basis of ligand field theory. The experimental magnetic susceptibilities for molybdenum ions, which are stabilized at the octahedral site in the perovskite lattice of Ba2ScMoⅤO6 and Sr2YMoⅤO6, were compared with the theoretical ones. We have tried to fit their temperature dependence of magnetic susceptibility with ligand field parameters, spin-orbit coupling constant ζSO, and orbital reduction parameter κ according to intermediate field coupling and strong field theory. Strong field coupling theory could not explain experimental curves without unrealistically large axial ligand field, since it ignores the mixing up between different state via spin-orbit interaction and ligand field. On the other hand, the intermediate field coupling theory could successfully reproduce experimental data in octahedral and trigonal ligand field. The fitting result demonstrates not only the fact that spin-orbit interaction is primarily responsible for the variation of magnetic behavior but also the fact that effective orbital overlap, enhanced by cubic crystal structure, reduces significantly orbital angular momentum as indicated by κ parameter.

• Journal of the Korean Magnetics Society
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• v.22 no.4
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• pp.117-120
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• 2012

Compounds such as NaN belong to an interesting class of materials in which a magnetic order may appear despite the lack of d electrons. The magnetic properties of these materials are ascribed to the partially filled p shells. Recently, on the basis of electronic structure calculations from first principles, it has been found that NaN is a ferromagnetic half-metal in rocksalt (RS) and zinc-blende (ZB) structures with half-metallic band gaps in majority electron channels. The former structure has appeared to be more stable. From the first-principles calculation, we found that the half-metallic properties of the bulk RS and ZB NaN are conserved at the RS(001) and ZB(110) surfaces. Due to the interactions between Na s and N p electrons, N atoms become positively polarized. In the RS NaN (001) the calculated values of the magnetic moments of the N atoms is about $0.73{\mu}_B$. The magnetic moment on the N atom in the top most layer of ZB(110) is slightly larger than that of the RS(001) surface, i.e., $0.75{\mu}_B$. The Na atoms in the both structure are hardly polarized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.231-232
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• 2008

The coupling between electric, magnetic, and structural order parameters results in the so-called multiferroics, which possess ferroelectricity, ferromagnetism, and/or ferroelasticity. The simultaneous ferroelectricity and ferromagnetism (magnetoelectricity) allow potential applications in information storage, spintronics, and in magnetic or electric field sensors. Perovskite compound $BiFeO_3$ (BFO) is antiferromagnetic below Neel temperature of 647K and ferroelectric with a high Curie temperature of 1043K. It exhibits weak magnetism at room temperature(RT) due to the residual moment from a canted spin structure. It is likely that non-stoichiometry and second-phase formation are the factors which cause leakage in BFO. It has been suggested that oxygen non-stoichiometry leads to valence fluctuations of Fe ions in BFO, resulting in high conductivity. To reduce the large leakage current of BFO, one attempt is fabricating donor doped BFO compounds and thin films. We report here the successful fabrication of the Nd, Ti co-doped $BiFeO_3$ ceramics and thin films by pulsed laser deposition technique.

• Journal of the Korean Magnetics Society
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• v.9 no.5
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• pp.223-226
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• 1999

We have investigated the magnetic properties and the electronic structures of Tc half-monolayer (0.5-ML) on Pd(001) using the full-potential linearized augmented plane wave(FLAPW) energy band method. We calculated the total energies for ferromagnetic and paramagnetic states to determine the stable magnetic state. The calculated results show that the total energy of the ferromagnetic state is lower than that of the paramagnetic one. The overlayer Tc 0.5-ML has considerably large magnetic moment $(2.09\;{\mu}_B)$, while the substrate Pd layers have been negatively polarized. The calculated density of states and total electrons inside the muffin-tin (MT) sphere are presented and discussed in relation with the magnetic properties.

• Journal of the Korean Magnetics Society
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• v.23 no.6
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• pp.179-183
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• 2013

The half-metallicity and magnetism for compounds of the $N_{(2-0.5n)}O_{0.5}nKCa$ (n = 0~4), which was based on the $d^0$ Heusler half-metals of $N_2KCa$ and $O_2KCa$, were investigated by means of first-principles band calculation method. From the calculated total magnetic moments and the density of states, we found that these three compounds have the half-metallicity. The magnetic moments of the N and O atoms in these compounds were considerably increased compared to those of pure $N_2KCa$ and $O_2KCa$. The K atoms have a large negative magnetic moments. The relationship between the value of magnetic moments for each atom and density of states are discussed.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.3
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• pp.175-179
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• 2022

Magnetic arc extinguishing technology is effective as an extinguishing device for low-voltage direct current (DC) circuit breakers with a resistive load of ≤4 kW. The separation distance between the magnet and the electrical contact must be shortened to increase the magnetic arc extinguishing force. However, if the magnet is installed too close to the electrical contact points, the magnet is exposed to high temperatures due to the arc current generated when the load current is cut off and the magnetism is lost. To solve this problem, the effective magnetic flux density at the electrical contact can be maintained high by placing the arc extinguishing magnet in a tandem structure with the electrical contact point between them, and the proper separation distance between the contact points and the magnet can be maintained. In addition, an electric arc extinguishing technology that emits arc energy using a series circuit of diode and resistor is used to suppress the continuous arc voltage generated by the inductive load. For the proposed circuit breaker, the breaking characteristics are analyzed through the breaking test for the DC load of the 760 V level, the load power of 4 kW, and the time constant of 5 ms, and an appropriate arc extinguishing design guideline is proposed.

• Journal of the Korean Magnetics Society
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• v.15 no.1
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• pp.7-11
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• 2005

A single slab in which one Ni(001) atom layer embedded between two of four Rh layers is considered to examine the oscillation of magnetic moment in each layer. The all electron total-energy full-potential linearized augmented plane wave(FLAPW) method was used to calculate the spin densities, magnetic moments, density of states(DOS), and the number of electrons within each muffin-tin(MT) sphere. The magnetic moment of the center layer Ni(C) in the system of 4Rh/Ni/4Rh is calculated to be 0.34${\mu}_B$, which is 40% have magnetic moment at the interface layers by strong band hybridization with Ni(C) when Ni(001) monolayers is inserted, and the magnetic moment shows a damped oscillation as we go from center Ni(C) layer to the surface Rh(S). From the calculated density of states, it is found that the Fermi level shifts inside the energy band of the Ni(C) in affection of Rh(001).

• Journal of the Korean Magnetics Society
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• v.19 no.5
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• pp.165-170
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• 2009

It is well-known that a meta-stable fcc bulk Fe has an antiferromagnetic (AFM) ground state and could be synthesized by growing Fe on a proper fcc metal substrate. In this study magnetism of Fe monolayers on nonmagnetic fcc transition metal (Cu, Rh, Pd, and Ag) (001) surfaces has been investigated using the all-electron full-potential linearized augmented plane wave method. The Fe monolayers on Rh(001) and Pd(001) surfaces were calculated to be stabilized in an AFM state, whereas the Fe monlayers on Cu(001) and Ag(001) surfaces are stabilized in a ferromagnetic (FM) state. Noting that Cu and Ag have the smallest and largest lattice constants and the fcc bulk Fe with a larger lattice constant is getting stabilized in a ferromagnetic state, it is unexpectable and interesting. The calculated magnetic moments of the Fe atoms on Cu, Rh, Pd, and Ag(001) surfaces are 2.811, 2.945, 2.987, and 2.990 $_{{\mu}B}$ in FM states and 2.624, 2.879, 2.922, and 3.001 $_{{\mu}B}$ in AFM states.