Browsing by Author "Liu, M."

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3D visualizations of nanoscale phase separation and ultrafast dynamic correlation between phases in (Na0.32K0.68)(0.95)Fe1.75Se2
(2019-03-25)
Cheng, P. C.
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Tzeng, W. Y.
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Chu, Y. J.
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Luo, C. W.
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Zhukov, A. A.
Phase separation of metallic and antiferromagnetic (AFM) insulating phases in alkaline iron selenides (A(x)Fe(2)-ySe(2)) continues to attract intense interest because the relationship between two peculiar features probably is a key to clarifying the pairing mechanism of A(x)Fe(2-y)Se(2) superconductors. Here we report that the three-dimensional (3D) visualizations of nanoscale phase separation in (Na0.32K0.68)(0.95)Fe1.75Se2 single crystals are revealed by hybrid focused-ion-beam scanning electron microscopy and the superconducting paths are fully percolative in 3D. Moreover, the phase-related ultrafast dynamics in (Na0.32K0.68)(0.95)Fe1.75Se2 is studied by dual-color pump-probe spectroscopy. The anomalous changes in the electron and acoustic phonon components of transient reflectivity change (Delta R/R) identify two characteristic temperatures T* similar to 100K (the onset temperature of coupling between the nanometallic and AFM phases) and T-H similar to 230K (the onset temperature of the metallic-interface phase). An energy-transfer channel between the nanometallic and AFM phases is inferred. This proposed channel provides insight into the pairing mechanism of alkaline iron selenide superconductors.
FUEL 133-Investigation into sulfur poisoning processes in Ni-based catalysts using quantum-chemical computations
(2008-04-06)
Wang, J. H.
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Lin, M. C.
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Liu, M.
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應用化學系
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應用化學系分子科學碩博班
Ultra-Low Switching Power RRAM Using Hopping Conduction Mechanism
(2012)
Chin, Albert
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Cheng, C. H.
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Chiu, Y. C.
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Zheng, Z. W.
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Liu, M.
Very low 0.4 pJ switching energy, fast 50 ns switching time, large > 10(5) retention window at 85 degrees C, and 10(6) cycling endurance were achieved in Ni/GeOx/SrTiOy/TaN RRAM. This RRAM device has negative temperature coefficient (TC) and ruled by bulk hopping conduction mechanism that lead to potentially better distribution. This is in sharp contrast to the positive TC and randomly distributed metallic filament RRAM. Such low switching energy is necessary for large-array NAND memory application, a unique merit of this RRAM device.