Browsing by Author "Huang, S. M."

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Observation of charge-transfer-driven antiferroelectricity in 3d-pyrochlore multiferroic Cu2OCl2
(2019-03-01)
Wu, H. C.
;
Yuan, J. K.
;
Chandrasekhar, K. D.
;
Lee, C. H.
;
Li, W. H.
Very recently, multiferroic behavior close to the boiling temperature of liquid nitrogen was reported in oxohalide-based Cu2OCl2. In this study, we have established yet another novel mechanism for the origin of charge ordering in multiferroic Cu2OCl2. The direct current (DC) magnetization, specific heat, and neutron diffraction measurements confirm the antiferromagnetic (AFM) ordering (T-N) of Cu2OCl2 near 70 K. The collinear AFM spin structure in Cu(2)OCl(2)was obtained from neutron powder diffraction experiments based on the fitting to the combination of two irreducible representations-Gamma(1)circle plus Gamma(2). Electrical properties, such as dielectric constant, pyroelectric current, and polarization-electric field hysteresis-loop measurements, together suggest a long-range antiferroelectric ordering near T-E approximate to 75 K. The charge transfer from Cl to O along the c-axis was found to induce antiferroelectricity near TE and is supported from ab initio calculations. This finding largely reduces the possibility of well-known Dzyaloshinskii -Moriya interaction in the observed multiferroic behaviors and provides insight into the various origins of high-T-c multiferroics. (C) 2018 Elsevier Ltd. All rights reserved.
Observation of strong electron dephasing in highly disordered Cu93Ge4Au3 thin films
(2007-07-27)
Huang, S. M.
;
Lee, T. C.
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Akimoto, H.
;
Kono, K.
;
Lin, J. J.
We report the observation of strong electron dephasing in a series of disordered Cu93Ge4Au3 thin films. A very short electron dephasing time possessing very weak temperature dependence around 6 K, followed by an upturn with further decrease in temperature below 4 K, is found. The upturn is progressively more pronounced in more disordered samples. Moreover, a lnT-dependent, but high-magnetic-field-insensitive, resistance rise persisting from above 10 K down to 30 mK is observed in the films. These results suggest a nonmagnetic dephasing process which is stronger than any known mechanism and may originate from the coupling of conduction electrons to dynamic defects.
Spin blockade with spin singlet electrons
(2012-12-24)
Sun, Y. C.
;
Amaha, S.
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Huang, S. M.
;
Lin, J. J.
;
Kono, K.
We observe a singlet spin blockade (SSB) in two-electron vertical double quantum dots where the single-electron transport is blocked for spin singlet electrons. In contrast to the conventional Pauli spin blockade with spin triplet electrons, this singlet spin blockade is observed under high magnetic field, where the doubly occupied states in one of the dots go beyond the singlet-triplet ground-state transition. The SSB region in Coulomb diamond measurements is in agreement with the two-electron excitation spectrum. A leakage current of 10 pA order is observed in SSB, consistent with the spin singlet lifetime due to random nuclear spin fluctuations. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4773304]
Spin Bottleneck in Resonance Tunneling through In0.04Ga0.96As/GaAs Vertical Double Quantum Dots
(2011-01-01)
Huang, S. M.
;
Tokura, Y.
;
Akimoto, H.
;
Kono, K.
;
Lin, J. J.
We study the electron resonance tunneling through double quantum dots with different g factors. We found that the resonance tunneling current is suppressed even if one of the Zeeman sublevels is aligned. The level broadening effect partially releases the blockade. The current maximum peak appears when the interdot detune is half of Zeeman energy difference of two quantum dots.
Spin Bottleneck in Resonant Tunneling through Double Quantum Dots with Different Zeeman Splittings
(2010-04-02)
Huang, S. M.
;
Tokura, Y.
;
Akimoto, H.
;
Kono, K.
;
Lin, J. J.
We investigated the electron transport property of the InGaAs/GaAs double quantum dots, the electron g factors of which are different from each other. We found that in a magnetic field, the resonant tunneling is suppressed even if one of the Zeeman sublevels is aligned. This is because the other misaligned Zeeman sublevels limit the total current. A finite broadening of the misaligned sublevel partially relieves this bottleneck effect, and the maximum current is reached when interdot detuning is half the Zeeman energy difference.