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Influence of Fragrances on Human Psychophysiological Activity: With Special Reference to Human Electroencephalographic Response
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Two Attic Funerary Stelai in the J. Paul Getty Museum
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Current medical research and opinion
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A versatile^ PC-based gamma ray monitor
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LED Back Light Units 산업의 성장전략에 관한 연구 = (A) study on the growth strategy of LED Back Light Units industry
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- 저자 : 김삼진 (검색결과 129 건)
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Effects of Cr Doping on the Electronic Structure of MnTe
김삼진,김광주,이정한,이희정,윤정범,정명화,김우철,김철성 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
The effects of Cr doping on the electronic structure of semiconducting MnTe have been investigated by using electron and optical spectroscopies. All CrxMn1-xTe samples grown as polycrystalline films by molecular beam epitaxy on Si(100) substrates showed a NiAs structure with little change in lattice parameters for x ≤ 0.15. X-ray photoelectron spectroscopy and spectroscopic ellipsometry results suggest the existence of spin-polarized Mn d bands in CrxMn1-xTe. The majority- and the minority-spin d bands are likely to be located ∽4 eV below and ∽3 eV above the Fermi level, respectively. The direct optical-band-gap of CrxMn1-xTe is found to gradually decrease with increasing x in the infrared region. A ferromagnetic behavior was observed for the CrxMn1-xTe films. The possible origin for the ferromagnetism is the coupling of Cr spins mediated by spin-polarized holes in the valence bands created through the hybridization between Te p and Cr d states. The effects of Cr doping on the electronic structure of semiconducting MnTe have been investigated by using electron and optical spectroscopies. All CrxMn1-xTe samples grown as polycrystalline films by molecular beam epitaxy on Si(100) substrates showed a NiAs structure with little change in lattice parameters for x ≤ 0.15. X-ray photoelectron spectroscopy and spectroscopic ellipsometry results suggest the existence of spin-polarized Mn d bands in CrxMn1-xTe. The majority- and the minority-spin d bands are likely to be located ∽4 eV below and ∽3 eV above the Fermi level, respectively. The direct optical-band-gap of CrxMn1-xTe is found to gradually decrease with increasing x in the infrared region. A ferromagnetic behavior was observed for the CrxMn1-xTe films. The possible origin for the ferromagnetism is the coupling of Cr spins mediated by spin-polarized holes in the valence bands created through the hybridization between Te p and Cr d states.
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Diluted Ferromagnetic Semiconductor in a Cr-Based MnTe Thin Film
김삼진,김철성,Jungbum Yoon,Kwang Joo Kim,정명화,Sung Hwan Bae,김우철 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.2
Mn1-xCrxTe (x = 0.05, 0.1, 0.15), a single phase of high crystalline quality, was successfully grown on a Si(100):B substrate by using molecular beam epitaxy (MBE). An investigation on the magnetic and the electric transport properties of the Mn1-xCrxTe (x = 0.05, 0.1, 0.15) films shows ferromagnetic properties unlike antiferromagnetic bulk MnTe materials. The temperature dependence of the magnetic susceptibility in the film with x = 0.10 exhibits a sharp ferromagnetic transitions at around 175 K. An obvious semiconducting behavior is shown in the temperature range from 20 K up to 300 K. Our X-ray results and magnetization data have verified the ferromagnetism for preparing Cr-cluster-free magnetic semiconductor thin films as candidate materials for potential spintronic applications.
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M¨ossbauer Studies on Superexchange Interactions in Fe3O4
김삼진,김철성,한은주 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.6
Fe3O4 has been studied by using M¨ossbauer spectroscopy and X-ray diffraction. The crystal isfound to have a cubic spinel structure with the lattice constant a0 = 8.3970 ± 0.0005 °A. The temperaturedependence of the magnetic hyperfine fields at 57Fe nuclei at the tetrahedral (A) and theoctahedral (B) sites is analyzed by using the N´eel theory of ferrimagnetism. The dominant superexchangeinteraction is found to be the antiferromagnetic intersublattice A − O − B superexchangeinteraction and its strength is JA−B = −23.4 kB. The intrasublattice A−O−A superexchange interactionis also antiferromagnetic with a strength of JA−A = −14.6 kB. The weakest superexchangeinteraction is the ferromagnetic B −O −B interaction: JB−B = 1.23 kB. The Debye temperaturesof the tetrahedral and the octahedral sites are found to be A = 351 ± 5 K and B = 322 ± 5 K,respectively.
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Thermal Variation of MgZn Nanoferrites for Magnetic Hyperthermia
김삼진,현성욱,김철성,Hyung Joon Kim 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.4
Mg1−xZnxFe2O4 (x = 0.2, 0.4, 0.5, 0.6, 0.8) nanoparticles were prepared for the characterizationof the crystallographic and magnetic properties. The Rietveld refinement for x-ray diffraction wasused to confirm that the Zn ion occupied on B-site for dopings over 0.5 doping. The lattice constant(a0) was increased from 8.3969 to 8.4100 ± 0.0001 °A with increasing Zn concentration. M¨ossbauerspectra of all samples were taken at room temperature and showed Fe3+ and Fe2+ valence states. The thermal properties of all samples were measured at 50 kHz and 25 mT. The heating temperaturewas increased up to 124 C until 0.5 doping of Zn ions, however it was decreased down to 69 C over0.5 doping of Zn ions. These results can be explained by the fact that the saturation magnetizationwas increased by Fe2+ ion, but, the heating temperature was decreased due to occupation of Znions on B-site for dopings above 0.5.
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Study on the Geometrically-frustrated Magnet Ni_(1/2)Fe_(1/2)Ga_2S_4
김삼진,명보라,김철성,오영제 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.2
We have investigated the spin-lattice relation in geometrical frustration by using an X-ray diffractometer (XRD), a superconducting quantum interference device (SQUID) magnetometer, and a Mössbauer spectroscopy. The crystal structure of the Ni_(1/2)Fe_(1/2)Ga_2S_4 studied here, was determined to be a 2-D triangular lattice structure of P-3m1 with lattice parameters of a_0 = 3.650 Å, and c_0 = 12.040 Å. From the temperature dependence of the molar susceptibility in an applied high field of H = 5 T measured by using a SQUID magnetometer, Ni_(1/2)Fe_(1/2)Ga_2S_4 had a strongly antiferromagnetic behavior due to the Curie-Weiss temperature θ_W = -71.6 K. The freezing temperature at the onset of the spin-freezing transition was T_f = 10.0 K under a low field of H = 100 Oe, similar to a spin glass system, and the frustration parameter was f (|θ_W|/T_N= 3.25. From the Mössbauer spectrum at 4.2 K, we noticed a severely distorted 8-line shape coming from spin fluctuations and an incommensurate spin structure. The freezing temperature (T_f = 10 K) related to the electric spin disorder was different from the Néel temperature (T_N = 22 K) influenced by microscopic disorder of the nuclear spin due to a strained spin caused by the distorted lattice from geometrical frustration, as indicated in the Mössbauer spectra.
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