Browsing by Author "Lin, J. G."

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Dynamic magnetic interaction in La2/3Sr1/3MnO3/BiFeO3 heterostructure
(2014-09-15)
Guo, H. Y.
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Lin, J. G.
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Yang, Jan Chi
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Chu, Y. H.
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材料科學與工程學系
The La2/3Sr1/3MnO3/BiFeO3 (LSMO/BFO) heterostructure is studied as probed by temperature-dependent ferromagnetic resonance (FMR). Consistent with the structure analysis, two FMR modes are found for both a single LSMO layer and a LSMO/BFO bilayer grown on DyScO3, corresponding to the strained and relaxed phases of LSMO. The FMR linewidth intensity vs temperature curve shows two maxima at 200 K and 140 K in the strained phase of LSMO/BFO bilayer, which is related to the magnetic excitations in BFO. Our results demonstrate a dynamic spin interaction between LSMO and BFO, suggesting an effective route to manipulate the magnetic properties of oxide heterostructures. (C) 2014 AIP Publishing LLC.
Low-temperature specific heat of superconductors - I. Historical perspective prior to 1986
(2019-10-01)
Ho, J. C.
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Lin, J. G.
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Lin, J. Y.
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Yang, H. D.
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交大名義發表
Specific heat is a fundamental thermodynamic quantity closely related to internal energy and entropy of a system. In superconductivity research, it has been playing important roles ever since the intriguing critical phenomenon was discovered. Looking back, though, calorimetric measurements, along with the relevant low-temperature techniques, improved slowly over decades. Erroneous conclusions were reached often in the beginning, but eventually several calorimetrically-derived key features formed part of the basis in the microscopic BCS theory and its extended versions. While unable to predict whether or when a given material would become superconducting, theories helped data analysis and guided new superconductors search. Many elements, alloys and compounds joined the long list of known superconductors over the 75-year period between 1911 and 1986. Specific heat data yielded characteristic parameters, and ascertained whether an observed transition was a bulk effect. In the later years, theoretical models or experimental results also revealed a few classes of unconventional superconductors, mostly involving the interplay between superconductivity and magnetism. This article is purposely focused, as historical perspective, on how such activities progressed. Only initial findings and some related reports are cited, leaving out much more detailed and better executed work published later. For the same reason, only select figures and discussions of cited articles, but not their full extent, are included.
Low-temperature specific heat of superconductors II: Progress in the new era
(2019-10-01)
Yang, H. D.
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Lin, J-Y
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Lin, J. G.
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Ho, J. C.
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交大名義發表
Beginning in the late 1980s, many unexpected superconductors have emerged. They raised not only the transition temperature limit but, just as importantly, the theoretical challenges beyond the BCS theory. Following the previous article on historical perspective of low-temperature specific heat of superconductors prior to 1986, we review briefly here some calorimetric studies on representative high-T-c and other novel superconductors discovered during the new era. Major emphasis is centered on special features of each set of temperature- and magnetic field-dependent specific heat data being fitted to select theoretical models. The models may involve multi-gap or a certain type of order-parameter symmetry.
Superconducting to spin-glass state transformation in beta-pyrochlore K(x)Os(2)O(6)
(2011-03-14)
Lee, C. C.
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Lee, W. L.
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Lin, J. -Y.
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Tsuei, C. C.
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Lin, J. G.
beta-pyrochore KOs(2)O(6), which shows superconductivity below similar to 9.7 K, has been converted into K(x)Os(2)O(6) (x less than or similar to 2/3-1/2) electrochemically to show spin-glass-like behavior below similar to 6.1 K. A room-temperature sample surface potential versus charge transfer scan indicates that there are at least two two-phase regions for x between 1 and 0.5. A rattling model of superconductivity for the title compound has been examined using electrochemical potassium de-intercalation. The significant reduction of superconducting volume fraction due to minor potassium reduction suggests the importance of defect and phase coherence in the rattling model. Magnetic susceptibility, resistivity, and specific heat measurement results have been compared between the superconducting and spin-glass-like samples.
Superconducting to spin-glass state transformation in beta-pyrochlore KxOs2O6
(2011-03-14)
Lee, C. C.
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Lee, W. L.
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Lin, J. -Y.
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Tsuei, C. C.
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Lin, J. G.
beta-pyrochore KOs2O6, which shows superconductivity below similar to 9.7 K, has been converted into KxOs2O6 (x less than or similar to 2/3-1/2) electrochemically to show spin-glass-like behavior below similar to 6.1 K. A room-temperature sample surface potential versus charge transfer scan indicates that there are at least two two-phase regions for x between 1 and 0.5. A rattling model of superconductivity for the title compound has been examined using electrochemical potassium de-intercalation. The significant reduction of superconducting volume fraction due to minor potassium reduction suggests the importance of defect and phase coherence in the rattling model. Magnetic susceptibility, resistivity, and specific heat measurement results have been compared between the superconducting and spin-glass-like samples.
Tertiary nitrogen nitrogen removal using simultaneous partial nitrification, anammox and denitrification (SNAD) process in packed bed reactor
(2017-05-01)
Chen, W. H.
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Chiang, Y. A.
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Huang, Y. T.
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Chen, S. Y.
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Sung, S.
The study aimed to polish wastewater effluent from an activated treatment system for nitrogen removal by a packed bed bioreactor (PBR). The nitrogen removal via simultaneous partial nitrification, anammox and denitrification (SNAD) process was investigated with different hydraulic retention times (HRTs). The results show that both effluent ammonia-and nitrate-nitrogen concentrations approached to 0 mg/L at the HRT as low as 3 h. The total nitrogen removal efficiency decreased from an average of 84% at both 18- and 24-h HRTs to 38% at 3-h HRT. This low nitrogen removal efficiency was due to the presence of incomplete degradation of organic nitrogen at shorter HRTs. The analysis using quantitative real-time polymerase chain reaction resolves that the ratio of ammonia-oxidizing bacteria (AOB) to the domain Eubacteria changed limited in the range between 2.8 and 4.0% during the continuous operation. Meanwhile, the nitrite-oxidizing bacteria (NOB) increased from 0.0 to 2.9% when the HRT was gradually reduced to 3 h. The anammox bacteria accounting for 30.5% of microbial consortia dominated the AOB and the NOB at the 3-h HRT. In sum, inorganic form of nitrogen in a typical wastewater plant effluent could be efficiently polished via SNAD process in the PBR. (C) 2017 Elsevier Ltd. All rights reserved.