• Journal of Magnetics
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• 제12권3호
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• pp.93-96
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• 2007

We investigated the electronic structure and magnetic properties of zinc-blende CrP/SrBi interface by using the all-electron full-potential linearized augmented plane wave method within the generalized gradient approximation. It is found that the half-metallicity is destroyed when the two half-metals are in contact. Magnetic moments of the atoms forming the supercell differ considerably from the respective values obtained for the bulk structures of the two materials. Cr atoms being and not being in contact with Bi atoms have magnetic moment 3.43 and $2.69{\mu}_B$, respectively. Bi atoms lose their majority electrons which results in their negative polarization. Alkaline Sr atoms are very weakly negatively polarized. The spin distribution within the supercell is such that well separated regions of positive and negative polarization are seen, especially around the layer of P atoms being in contact with the layer of Sr atoms.

• Journal of Magnetics
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• 제10권1호
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• pp.1-4
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• 2005

We investigated the electronic structures and the magnetic properties of Ti-based intermetallic system of CoTi/FeTi/CoTi(110) surface and interface by using the all-electron full potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation (GGA). The calculated magnetic moments of interface Co and Fe atoms are 0.65 and 0.15 μ/sub B/, respectively. Surface and interface magnetism of CoTi/FeTi/CoTi(110) are discussed using the calculated density of states (DOS) and the spin densities.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.207-216
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• 2000

Soft x-ray standing waves produced by a multilayer interference substrate add depth-sensitivity to magnetic circular dichroism to resolve changes in Co magnetism across a 10 ${\AA}$ distance from the Co center to the Co-Pd interface of a Pd/Co/Pd trilayer having in-plane magnetization. Large enhancements of in-plane orbital and spin magnetic moments, as well as the number of d holes, are strongly localized in thin interface layer. These results provide new insight into the phenomenon of magnetic anisotropy at buried interfaces, and suggest a broad applicability of such standing wave measurements to interface magnetism studies.

• Journal of Magnetics
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• 제4권4호
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• pp.107-110
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• 1999

In order to investigate the magnetism of Ru submonolayer on Pb(001), we have performed first-principles calculations for half-layer of Ru on Pd(001) using the full-potential linearzed augmented plane wave (FLAPW) method. We have found that the magnetic moment of Ru for 0.5 layer is 2.21 B. It is found that substrate Pd layers are polarized by the 0.5 Ru overlayer to have significant magnetic moments. Our results are compared with those obtained by the anomalous Hall effect. The calculated electronic structures, i,e., the spin densities and density of states are presented and discussed in relation with magnetic properties.

• 한국진공학회지
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• 제12권S1호
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• pp.60-62
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• 2003

In this study we report the results of ab initio first-principles calculations to investigate the possibility of metamagnetic behavior in Fe$_3$Al alloy. We used the WIEN2k package of full-potential linearized-augmented- plane-wave method within the local-spin-density approximation to the density-functional theory. The exchange-correlation functional is the generalized-gradient approximation of Perdew-Burke-Ernzerhof. The theoretical lattice constant, which is about 0.5% smaller than the experimental one, is obtained by minimizing the total energy. If the volume decreases about 9 % from the equilibrium, the total magnetic moment decreases abruptly from 4.6 $\mu_{B}$/f.u. to 4.0 $\mu_{B}$/f.u. Since this change is considerably large (∼14%), it is possible to measure by a simple high-pressure experiment at about 180 kbar.

• 한국자기학회지
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• 제5권5호
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• pp.767-771
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• 1995

The atomic structure and magnetic properties of $LaCo_{13}$ amorphous alloy have been investigated and compared with those of its crystalline counterpart. It has been confirmed that the amorphous alloy is composed of the icosahedral clusters with a $NaZn_{13}$-type structure. The magnetic moment and the spin- wave stiffness constant obtained from the magnetic measurements in the amorphous state are larger than those in the crystalline state. The Curie temperature estimated from the reduced magnetization curve for the former is much higher than the value for the latter. The localized magnetic moment character in the amorphous state is stronger than that in the crystalline state.

• 한국자기학회지
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• 제1권1호
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• pp.1-5
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• 1991

다결정${(Fe_{2}O_{3})}_{1-x-y}{(In_{2}O_{3})}_{x}{(Eu_{2}O_{3})}_{y}$(x=0.01, y=0.02과 x=0.02, y=0.03)의 자기적 성질을 X선 회절, $M\"{o}ssbauer$ 효과 방법과 자기이력 측정에 의해서 연구하였다. X선 회절결과는 이들 시료의 결정구조는 $\alpha-Fe_{2}O_{3}$와 같음을 보인다. 사중극자 분열과 평균 반폭치 분석으로부터 x=0.01과 y=0.02인 시료는 Morin 전이를 보이며, x=0.02와 y=0.03시료에서 반 강자성 벡타와 결정축[111]사이의 각은 온도의 증가에 따라 약 $35^{\circ}$로부터 (111) 평면에 놓이기 까지 변한다. 초미세 자기장의 온도 의존성은 스핀파 이론을 써서 분석하였다. 상온에서의 이성질체 이동값은 약 0.35mm/s로 이는 시료내의 철의 이온값은 $3^{+}$임을 의미하는 것이다. 이성질체 이동의 온도의존성은 Delbye모형을 써서 분석하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.370.1-370.1
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• 2014

Giant magnetoresistance (GMR), tunneling magnetoresistance (TMR), and magnetic random-access memory (MRAM) are currently active areas of research. Magnetite, Fe3O4, is predicted to possess as half-metallic nature, ~100% spin polarization (P), and has a high Curie temperature (TC~850 K). On the other hand, Spinel ferrite CoFe2O4 has been widely studies for various applications such as magnetorestrictive sensors, microwave devices, biomolecular drug delivery, and electronic devices, due to its large magnetocrystalline anisotropy, chemical stability, and unique nonlinear spin-wave properties. Here we have investigated the magneto-transport properties of epitaxial CoxFe3-xO4 thin films. The epitaxial CoxFe3-xO4 (x=0; 0.4; 0.6; 1) thin films were successfully grown on MgO (100) substrate by molecular beam epitaxy (MBE). The quality of the films during growth was monitored by reflection high electron energy diffraction (RHEED). From temperature dependent resistivity measurement, we observed that the Werwey transition (1st order metal-insulator transition) temperature increased with increasing x and the resistivity of film also increased with the increasing x up to $1.6{\Omega}-cm$ for x=1. The magnetoresistance (MR) was measured with magnetic field applied perpendicular to film. A negative transverse MR was disappeared with x=0.6 and 1. Anomalous Hall data will be discussed.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.592-602
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• 2021

Thorium compounds have attracted immense scientific and technological attention with regard to both fundamental and practical implications, owing to unique chemical and physical properties like high melting point, high density and thermal conductivity. Hereby, we investigate the mechanical and thermodynamic stability and report on the structural, electronic and magnetic properties of new silicon-doped cubic ternary thorium phosphides ThSi_xP_1-x (x = 0, 0.25, 0.5, 0.75 and 1). The first-principles density functional theory procedure was adopted within full-potential linearized augmented plane wave (FP-LAPW) method. The exchange and correlation potential terms were treated within Generalized-Gradient-Approximation functional modified by Perdew-Burke-Ernzerrhof parameterizations. The proposed compounds showed mechanical and thermodynamic stable structure and hence can be synthesized experimentally. The calculated lattice parameters, bulk modulus, total energy, density of states, electronic band structure and spin magnetic moments of the compounds revealed considerable correlation to the Si substitution for P and the relative Si/P doping concentration. The electronic and magnetic properties of the doped compounds rendered them non-magnetic but metallic in nature. The main orbital contribution to the Fermi level arises from the hybridization of Th(6d+5f) and (Si+P)3p states. Reported results may have potential implications with regard to both fundamental point of view and technological prospects such as fuel materials for clean nuclear energy.

• 한국자기학회지
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• 제26권2호
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• pp.39-44
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• 2016

대표적 열전물질인 비스무스 텔루라이드에 자성원자를 도핑한 합금에 대한 구조 및 전자적 그리고 자기적 성질에 관한 연구는 고효율 열전물질의 개발이라는 목적뿐만 아니라 특이한 자기적 상호작용 규명 및 위상절연체 분야에서도 큰 관심을 끌고 있다. 본 연구에서는 희토류 원자로서 매우 국소화된 f 전자를 갖는 Gd이 Bi을 치환하여 도핑된 비스무스 텔루라이드 합금의 자성 안정성을 밀도범함수(Density Functional Theory)에 입각하여 제일원리적으로 연구하기 위하여 모든 전자(all-electron) FLAPW(full-potential linearized augmented plane-wave) 방법을 이용하여 전자구조 계산을 수행하였다. 전자간 교환-상관 상호작용은 일반기울기 근사법(Generalized Gradient Approximation)을 도입하여 계산하였으며, 국소화된 f 전자를 기술하는 데 필요한 Hubbard+U 보정과 스핀-궤도 각운동량 상호작용은 제2 변분법적 방법을 이용하여 고려하였다. 계산 결과, 강자성 안정성을 보이는 Gd 덩치계와 다르게 이 합금은 강자성과 반강자성의 총에너지 차이가 ~1 meV/Gd 정도의 아주 작은 값으로 얻어져서, 그 자성 안정성은 결함이나 strain 등에 의한 구조변화에 민감하게 의존하여 변할 수 있음을 알 수 있었다. 특히 Gd 스핀자기모멘트는 덩치에서의 값에 비해 감소하였고, Gd에 가장 가까운 Te에 유도 자기모멘트가 형성되는 것으로 미루어 Te를 매개로 한 자성상호작용이 자성 안정성을 결정하는 데에 중요한 역할을 하는 것으로 예측할 수 있었다.