• Journal of Magnetics
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• v.15 no.2
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• pp.51-55
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• 2010

The electronic and magnetic properties of Cu-doped GaN with a Cu concentration of 6.25% and 12.5% are examined theoretically using the full-potential linear muffin-tin orbital method. The magnetic moment of Cu atoms decreases with increasing Cu concentration. The spin-polarization of Cu atoms is reduced due to the Cu d-d interaction depending on the distance between the nearest neighbouring Cu atoms. Cu atoms exhibits a clustering tendency in GaN. For Cu-adsorbed GaN thin films with a surface coverage of 0.25, the ferromagnetic state is found to be the energetically favourable state with an induced magnetic moment of $0.54\;{\mu}_B$ per supercell.

• Journal of Magnetics
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• v.11 no.1
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• pp.20-24
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• 2006

Very recently, it was presented that the one dimensional (1D) CuO atomic chains can maintain large magnetic moments. In this work, we analyzed m-resolved density of states (DOS) to understand the peculiar spin polarization occurred in Cu atoms. It was found that the $\mid{m}\mid=1$ states play an essential role in the spin polarization of Cu atoms. In addition, we calculated magnetic anisotropy energy (MAE) and observed that the distribution of MAE is strongly sensitive to the interatomic distance between Cu and O atoms. Besides, it was revealed that the contribution to MAE comes for the second half of Brillouin zone (BZ).

• Journal of the Korean Magnetics Society
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• v.26 no.4
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• pp.119-123
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• 2016

We have studied electronic and magnetic structure of cubane-type Cu magnetic molecule using density functional method. The calculated density of states show that Cu has 3d $x^2-y^2$ hole orbital because of short distances between Cu atom and in-plane 4 ligand atoms. The calculated total energy with in-plane antiferromagnetic spin configuration is lower than those of ferromagnetic configurations. The calculated exchange interaction J between in-plane Cu atoms is much larger than those between out-plane Cu atoms, since the $x^2-y^2$ hole orbital ordering of Cu 3d orbitals induces strong super-exchange interaction between in-plane Cu atoms.

• Journal of Magnetics
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• v.12 no.2
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• pp.59-63
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• 2007

Ferromagnet/Semiconductor heterostructures have attracted much attention because of their potential applications in spintronic devices. We investigated the electronic structures and magnetism of monolayer Fe on $CuGaSe_2(001)$ by using the all-electron full-potential linearized augmented plane-wave method within a generalized gradient approximation. We considered the monolayer Fe deposited on both the CuGa atoms terminated (CuGa-Term) and the Se atom terminated (Se-Term) surfaces of $CuGaSe_2(001)$. The calculated magnetic moment of the Fe atom on the CuGa-Term was about $2.90\;{{\mu}_B}$. Those of the Fe atoms on the Se-Term were in the range of $2.85-2.98\;{{\mu}_B}$. The different magnetic behaviors of the Fe atoms on two different surfaces were discussed using the calculated layer-projected density of states.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.45-49
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• 2006

The changes in the optical anisotropy of the clean Cu(110) and the oxygen covered Cu(110) surfaces due to Cu growth have been studied by reflectance difference spectroscopy(RDS). We have monitored the growth mode of Cu atoms on Cu(110) and Cu(110)-(2XlO surfaces at 250K and checked the surfactant effect of oxygen during the Cu growth. For Cu grow on Cu(110) and Cu(110)-(2Xl)O surface at low temperature, we observed evidence for the layer-by-layer growth mode with change of 4.25eV peak intensity.

• Korean Journal of Materials Research
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• v.8 no.9
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• pp.837-842
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• 1998

As the size of the integrated circuit is scaled down the importance of Si cleaning has been emphasized. One of the major concerns is abut the removal of metallic impurities such as Cu and Fe on Si surface. In this study, we intentionally contaminated Cu and Fe on the Si wafers and cleaned the wafer by cleaning splits of the chemical mixture of $\textrm{H}_2\textrm{O}_2$ and HF and the combination of HF treatment with UV/$\textrm{O}_3$ treatment. The contamination level was monitored by TXRF. Surface microroughness of the Si wafers was measured by AFM. The Si wafer surface was examined by SEM. AES analysis was carried out to analyze the chemical composition of Cu impurities. The amount of Cu impurities after intentional contamination was abut the level of $\textrm{10}^{14}$ atoms/$\textrm{cm}^2$. The amount of Cu was decreased down to the level of $\textrm{10}^{10}$ atoms/$\textrm{cm}^2$ by cleaning splits. The repeated treatment exhibited better Cu removal efficiency. The surface roughness caused by contamination and removal of Cu was improved by repeated treatment of the cleaning splits. Cu were adsorbed on Si surface not in a thin film type but in a particle type and its diameter was abut 100-400${\AA}$ and its height was 30-100${\AA}$. Cu was contaminated on Si surface by chemical adsorption. In the case of Fe the contamination level was $\textrm{10}^{13}$ atoms/$\textrm{cm}^2$ and showed similar results of above Cu cleaning. Fe was contaminated on Si surface by physical adsorption and as a particle type.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.5
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• pp.211-216
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• 2003

The $Cu[SO_3(CH_2)_4SO_3$］ㆍ$4H_2O$ compound was synthesized. The three-dimensional structure of $Cu[SO_3(CH_2)_4SO_3$］ㆍ$4H_2O$ compound was determined. The copper atom is bridged by 4 oxygen atoms of 4 water molecules and 2 oxygen atoms of butanedisulfonate. The butyl chain in the plane of four copper atoms is oriented parallel and perpendicular to the one of plane axis, alternatively. Magnetic data indicate that this compound behaves a typical paramagnetic.

• Journal of Powder Materials
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• v.1 no.1
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• pp.79-84
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• 1994

The mechanism of activated sintering of tungsten powder was discussed in terms of diffusion and segregation of activator atoms at W grain boundaries. Shrinkage behaviours of W-0.2wt.% Ni, W-0.2wt.% Cu or pure W powder compacts during sintering at low temperatures of 900~ $1200^{\circ}C$ were investigated. It was found that the Cu additive inhibits sintering process causing lower densification than pure W compact while remarkable shrinkage occurred in the Ni added W powder. Such contrary effect was explained by comparing self diffusion processes along Ni or Cu segregated W boundaries in which Ni segregants enhance but Cu atoms retard the migration of W atoms at W boundaries.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.159-159
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• 2000

Initial growth mode of Nb on Cu(100) is studied by scanning tunneling microscopy (STM) and density functional theory. Nb/Cu is immiscible at room temperature, but isolated Nb atoms are expected to be incorporated up to the second layer by DFT. STM shows that Nb atoms mix with Cu atoms in the first layer at room temperature and diffuse into the second layer upon annealing. In the second layer, Nb/induced features are preferentially found at step edges and appear as bright dots surrounded by dark rings. Details of comparison between experiment and theory will be discussed.

• Journal of the Semiconductor & Display Technology
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• v.9 no.3
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• pp.1-4
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• 2010

First-principles calculations based on spin density functional theory are performed to study the spin-resolved electronic properties of AlN doped with a Cu concentration of 6.25%-18.75%. The ferromagnetic state is more energetically favorable state than the antiferromagnetic state or the nonmagnetic state. For $Al_{0.9375}Cu_{0.0625}N$, a global magnetic moment of 1.26 mB per supercell, with a localized magnetic moment of 0.75 $m_B$ per Cu atom is found. The magnetic moment is reduced due to an increase in the number of Cu atoms occupying adjacent cation lattice position. For $Al_{0.8125}Cu_{0.1875}N$, the magnetism of the supercell disappears by the interaction of the neighboring Cu atoms. The nonmagnetic to ferromagnetic phase transition is found to occur at this Cu concentration. The range of concentrations that are spin-polarized should be restricted within very narrow.