The Experts below are selected from a list of 24435 Experts worldwide ranked by ideXlab platform
Seigo Tarucha - One of the best experts on this subject based on the ideXlab platform.
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ground state Transitions beyond the singlet triplet Transition for a two electron quantum dot
Physical Review B, 2007Co-Authors: Yoshifumi Nishi, Guy Austing, J A Gupta, Yasuhiro Tokura, Seigo TaruchaAbstract:We studied electrostatic confinement effects on correlated electronic states in vertical quantum dots in high magnetic fields. We prepared vertical quantum dots with different lateral confinement strengths and investigated the magnetic field evolution of the electronic states. We observed that the formation of the maximum density droplet state corresponding to filling factor $\ensuremath{\nu}=1$ shifts to lower magnetic field as the lateral confinement energy becomes weaker. In addition, we found a ground-state Transition in the $\ensuremath{\nu}l1$ regime for the most weakly laterally confined two-electron quantum dot that is predicted to appear beyond an easily accessible magnetic field in standard vertical quantum dots more typically investigated.
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spin configurations in circular and rectangular vertical quantum dots in a magnetic field three dimensional self consistent simulations
Physical Review B, 2005Co-Authors: Dmitriy V Melnikov, Seigo Tarucha, P Matagne, Jeanpierre Leburton, D G Austing, G Yu, John Fettig, Nahil SobhAbstract:The magnetic field dependence of the electronic properties of real single vertical quantum dots in circular and rectangular mesas is investigated within a full three-dimensional multiscale self-consistent approach without any \'a priori assumptions about the shape and strength of the confinement potential. The calculated zero field electron addition energies are in good agreement with available experimental data for both mesa geometries. Charging diagrams in a magnetic field for number of electrons up to five are also computed. Consistent with the experimental data, we found that the charging curves for the rectangular mesa dot in a magnetic field are flatter and exhibit less features than for a circular mesa dot. Evolution of the Singlet-Triplet energy separation in the two electron system for both dot geometries in magnetic field was also investigated. In the limit of large field, beyond the Singlet-Triplet Transition, the Singlet-Triplet energy difference continues to become more negative in a circular mesa dot without any saturation within the range of considered magnetic fields while it is predicted to asymptotically approach zero for the rectangular mesa dot. This different behavior is attributed to the symmetry ``breaking'' that occurs in the singlet wave-functions in the rectangular mesa dot but not in the circular one.
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Two-stage Kondo effect in a quantum dot at a high magnetic field.
Physical review letters, 2002Co-Authors: W. G. Van Der Wiel, Seigo Tarucha, S. De Franceschi, J. M. Elzerman, Leo P. Kouwenhoven, Junichi Motohisa, F. Nakajima, Takashi FukuiAbstract:We report a strong Kondo effect (Kondo temperature approximately 4 K) at high magnetic field in a selective area growth semiconductor quantum dot. The Kondo effect is ascribed to a Singlet-Triplet Transition in the ground state of the dot. At the Transition, the low-temperature conductance approaches the unitary limit. Away from the Transition, for low bias voltages and temperatures, the conductance is sharply reduced. The observed behavior is compared to predictions for a two-stage Kondo effect in quantum dots coupled to single-channel leads.
Yoshifumi Nishi - One of the best experts on this subject based on the ideXlab platform.
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ground state Transitions beyond the singlet triplet Transition for a two electron quantum dot
Physical Review B, 2007Co-Authors: Yoshifumi Nishi, Guy Austing, J A Gupta, Yasuhiro Tokura, Seigo TaruchaAbstract:We studied electrostatic confinement effects on correlated electronic states in vertical quantum dots in high magnetic fields. We prepared vertical quantum dots with different lateral confinement strengths and investigated the magnetic field evolution of the electronic states. We observed that the formation of the maximum density droplet state corresponding to filling factor $\ensuremath{\nu}=1$ shifts to lower magnetic field as the lateral confinement energy becomes weaker. In addition, we found a ground-state Transition in the $\ensuremath{\nu}l1$ regime for the most weakly laterally confined two-electron quantum dot that is predicted to appear beyond an easily accessible magnetic field in standard vertical quantum dots more typically investigated.
Barbara Sieklucka - One of the best experts on this subject based on the ideXlab platform.
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reversible single crystal to single crystal transformation in photomagnetic cyanido bridged cd4m2 octahedral molecules
Inorganic Chemistry, 2017Co-Authors: Tomasz Korzeniak, Robert Jankowski, Marcin Koziel, Dawid Pinkowicz, Barbara SiekluckaAbstract:Two new hexanuclear octahedral cyanido-bridged clusters, {[CdII(bpy)2]4[WIV(CN)8]2}·10H2O (Cd4W2) and {[CdII(bpy)2]4[MoIV(CN)8]2}·10H2O (Cd4Mo2), have been obtained and characterized structurally and photomagnetically. Both compounds show a very rare and reversible single-crystal-to-single-crystal transformation upon dehydration accompanied by marked color changes in the case of Cd4W2. Moreover, irradiation of Cd4Mo2 using 436 nm light induces a reversible photomagnetic effect due to the LIESST-like singlet–triplet Transition at the MoIV center. Analogous photomagnetic experiments for Cd4W2 did not lead to any significant change of its magnetic moment.
Wei Huang - One of the best experts on this subject based on the ideXlab platform.
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direct population of triplet excited states through singlet triplet Transition for visible light excitable organic afterglow
Chemical Science, 2019Co-Authors: Jie Yuan, Runfeng Chen, Xingxing Tang, Ye Tao, Lu Jin, Cailin Chen, Xinhui Zhou, Chao Zheng, Wei HuangAbstract:Invoking efficient afterglow in metal-free organic molecules represents an important material advancement. However, organic afterglow suffers from low intensity and efficiency and generally needs to be excited by UV light owing to its spin-forbidden phosphorescent nature that essentially requires facile intersystem crossing (ISC). Here, we propose a strategy to bypass the traditional ISC through facilitating singlet–triplet Transition to directly populate triplet excited states from the ground state by combining synergetic effects of both heavy/hetero-atom incorporation and aromatic aggregation. Verified by systematic experimental and computational investigations, this unique singlet-to-triplet absorption results in a much improved organic afterglow quantum efficiency up to 9.5% with a prolonged lifetime of 0.25 s under visible-light irradiation. Fundamentally, this work illustrates for the first time the great potential of the direct population method to red-shift the excitation wavelength and improve the afterglow efficiency, offering important clues for the development of triplet-state involved organic optoelectronic technologies.
Hadas Shtrikman - One of the best experts on this subject based on the ideXlab platform.
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singlet triplet Transition in a single electron transistor at zero magnetic field
Physical Review B, 2003Co-Authors: Andrei Kogan, David Goldhabergordon, M A Kastner, G Granger, Hadas ShtrikmanAbstract:We report sharp peaks in the differential conductance of a single-electron transistor (SET) at low temperature for gate voltages at which charge fluctuations are suppressed. For odd numbers of electrons we observe the expected Kondo peak at zero bias. For even numbers of electrons we generally observe Kondo-like features corresponding to excited states. For the latter, the excitation energy often decreases with gate voltage until a new zero-bias Kondo peak results. We ascribe this behavior to a Singlet-Triplet Transition in zero magnetic field driven by the change of shape of the potential that confines the electrons in the SET.