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505 results on '"Yang, H. D."'

253. Structural, transport and optical properties of (La0.6Pr0.4)0.65Ca0.35MnO3 nanocrystals: a wide band-gap magnetic semiconductor.

Author

Kumar, Satyam, Dwivedi, G. D., Kumar, Shiv, Mathur, R. B., Saxena, U., Ghosh, A. K., Joshi, Amish G., Yang, H. D., and Chatterjee, Sandip

Subjects
NANOPARTICLES, NANOCRYSTALS, NANOCRYSTAL synthesis, OPTICAL properties, ELECTRO-optical effects, MAGNETIC materials
Abstract

(La0.6Pr0.4)0.65Ca0.35MnO3 system has been synthesized via a sol–gel route at different sintering temperatures. Structural, transport and optical measurements have been carried out to investigate (La0.6Pr0.4)0.65Ca0.35MnO3 nanoparticles. Raman spectra show that Jahn–Teller distortion has been decreased due to the presence of Ca and Pr in A-site. Magnetic measurements provide a Curie temperature around 200 K and saturation magnetization (MS) of about 3.43μB/Mn at 5 K. X-ray photoemission spectroscopy study suggests that Mn exists in a dual oxidation state (Mn3+ and Mn4+). Resistivity measurements suggest that charge-ordered states of Mn3+ and Mn4+, which might be influenced by the presence of Pr, have enhanced insulating behavior in (La0.6Pr0.4)0.65Ca0.35MnO3. Band gap estimated from UV-Vis spectroscopy measurements comes in the range of wide band gap semiconductors (∼3.5 eV); this makes (La0.6Pr0.4)0.65Ca0.35MnO3 a potential candidate for device application. [ABSTRACT FROM AUTHOR]

Published
2015
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256. Magnetic ordering in double-chainPrBa2Cu4O8

Author

Li, W.-H., primary, Wu, S. Y., additional, Lin, Y.-C., additional, Lee, K. C., additional, Lynn, J. W., additional, Weng, S. S., additional, Hong, I. P., additional, Lin, J.-Y., additional, and Yang, H. D., additional

Published
1999
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262. Structural and Magnetic Properties of Y-doped La0.5Sr0.5MnO3 Manganite System: Evidence of Step-like Magnetization.

Author

Taran, Subhrangsu, Sun, C. P., Huang, C. L., Yang, H. D., Nigam, A. K., Chaudhuri, B. K., and Chatterjee, S.

Subjects
LANTHANUM compounds, MANGANESE oxides, MANGANITE, MAGNETIC properties of metals, TRANSPORT properties of metal, DOPING agents (Chemistry)
Abstract

The magnetic and transport properties of bulk doped manganite, La05-yYySr0.5MnO3 have been studied as a function of yttrium doping, y, for 0 ≤ y ≤ 0.25. In the absence of the yttrium this is a well studied half-doped manganite which is a metallic ferromagnet. The end members of this system (with y = 0 and 0.25) are found to be structurally different (rhombohedral and orthorhombic, respectively) due to the large distortions caused by the yttrium. These distortions make this series of compounds particularly interesting. The magnetization obtained in zero field cooled (ZFC) and field cooled (FC) studies show dramatic changes as the value of y is raised above 0.05. The magnetic behavior is further investigated by a study of the hysteresis loops, frequency dependent susceptibility and studies of the magnetic relaxation. The results are understood in terms of the average size of the cation on the A site, A>, and the variance, σ² (=∑yi²ri² - A>²). The value of the variance, σ², increases rapidly with doping, y, induces melting of the long range ferromagnetic ordering, exhibiting a stepwise variation of magnetization (metamagnetic like). Based on the present results a magnetic phase diagram has been drawn demonstrating different magnetic phase sequences with the variation of σ². [ABSTRACT FROM AUTHOR]

Published
2015
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285. Calorimetric Studies on the Pairing State of Multiband Superconductivity.

Author

Yang, H. D. and Lin, J. Y.

Subjects
SUPERCONDUCTIVITY, MAGNETIC fields, CALORIMETRY, SPECIFIC heat, SUPERCONDUCTORS
Abstract

After applying numerical fitting to the data of the electronic part of specific-heat without and with magnetic fields[S1], one might be able to identify that a certain model, such as simple BCS-like s-wave, anisotropic s-wave, d-wave, two-gap or other combination, is better to describe the order parameters of a superconducting state. Multiband, in particular two-band models have been successfully used to describe the superconducting pairing state of some novel superconductors, such as MgB2, YNi2B2C, NbSe2 and FeSe. Compared to other sophisticated experiments, the specific-heat measurement has proven to be the one of most powerful tools to address this important issue toward the understanding of the origin of novel superconductor. [ABSTRACT FROM AUTHOR]

Published
2011

286. High-Field Magnetization of the Distorted Spin Frustration System Ni5(TeO3)4Br2.

Author

Her, J. L., Suga, K., Kindo, K., Takeyama, S., Berger, H., Yang, H. D., and Matsuda, Y. H.

Subjects
MAGNETIZATION, MAGNETIC fields, ANISOTROPY, ELECTRON paramagnetic resonance, ANTIFERROMAGNETISM
Abstract

We performed high-field magnetization measurements, M( H), on the Ni5(TeO3)4Br2 by using a pulse magnet. The Ni2+ ions ( S = 1) of this compound form a two dimensional distorted spin frustrated system (distorted kagome lattice), and undergo a Neel transition at T N∼29 K, due to the anisotropy. Below T N, a complex spin arrangement which contains ten spin sub-lattices was suggested by neutron scattering and electron spin resonance studies. We observed a step-like transition at H c∼11 T when T< T N. By contrast, at T> T N, the field-dependent magnetization curves behaved like a straight line. The H c is close to those obtained by previous spin resonance studies of Ni5(TeO3)4Br2 and Ni5(TeO3)4Cl2 in which a spin-flop-like transition was proposed to explain the field-dependent resonance spectra. Interestingly, the observed change in magnetization (Δ M) at H c corresponds to nearly one-half of the magnetic moment of Ni2+ ion, suggesting that the observed step-like behavior possibly corresponds to a spin-flip-like transition (i.e. from antiferromagnetic state to ferrimagnetic state). In addition, in the high-field region ( H> H c), the M( H) curves did not show plateau behavior, but exhibited the straight lines having finite slopes without any sign of saturation up to 55 T. [ABSTRACT FROM AUTHOR]

Published
2010
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298. Antimalarial activity of a stilbene glycoside from Pleuropterus ciliinervis.

Author

Lee, S. I., Yang, H. D., Son, I. H., and Moon, H. I.

Subjects
*PARASITES, *PESTS, *MOSQUITOES, *HERBARIA, *STILBENE, *GLUCOSIDES, *PHENYL compounds, *ANTIMALARIALS
Abstract

The article focuses on the study about the antimalarial activity of a stilbene glucoside evident in Pleuropterus ciliinervis parasites. Pleuropterus ciliinervis was gathered in the O-Dae mountains in South Korea and was deposited in the herbarium of the Pharmacognosy Laboratory at the Sung Kyun Kwan University. The authors found out that only the n-butanolic exhibited reasonable antimalarial activity. A table that shows the measurement of the antimalarial activity of the Pleuropterus ciliinervis is also presented.

Published
2008
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299. Structural, electronic and magnetic properties of ErFeMn and ErFeMnH4.7 compounds.

Author

Mylswamy, S., Drozd, V., Liu, R. S., Bagkar, N. C., Chou, C. C., Sun, C. P., Yang, H. D., Paul-Boncour, V., Marchuk, I., Filipek, S. M., Sheu, H.-S., and Jang, L.-Y.

Subjects
MAGNETIC properties, X-ray absorption near edge structure, X-ray diffraction, HYDROGENATION, QUANTUM interference
Abstract

ErFeMn intermetallic alloy after exposure to high hydrogen pressure transformed into the ErFeMnH4.7 hydride. Both parent material and hydride were investigated for their structural, electronic and magnetic properties by synchrotron XRD (x-ray diffraction), XANES (x-ray absorption near edge structure) and SQUID (superconducting quantum interference device), respectively. Hydrogenation did not change the structure symmetry but caused large expansion of the lattice parameters. Mn and Fe K-edge XANES study of the parent alloy and its hydride reveals that charge on both Mn and Fe atoms remains the same and slightly increases after hydrogenation. Hydrogenation of ErFeMn alloy also caused decrease in the magnetic moment. [ABSTRACT FROM AUTHOR]

Published
2007
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