Room-temperature spin coherence in zinc blende CdSe quantum dots studied by time-resolved Faraday ellipticity

Zhang, Zhengbing; Jin, Zuanming; Ma, Hong; Xu, Yue; Lin, Xian; Ma, Guohong; Sun, Xiaolan

doi:10.1016/j.physe.2013.08.022

Cited by 16 publications

(15 citation statements)

References 33 publications

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“…Thus the measurements seem to be sensitive to the spin coherent time of the dots and to the electron spin flip, which in the case of smaller CdSe NCs becomes more dominant and compromises the charge separation effect.Smaller charge separation effect could be also predicted due to changes in the excited states lifetime upon cooling. Spin coherence and excited states life times are expected to be two orders of magnitude longer at low tempertures 31,32,33. However, in the helical chiral molecules it has been shown that below ‫ܭ051‬ the chiral molecules used in this study undergo structure and electrical phase transition, 34,35 thus rendering a weaker chiral induced state which may shorten dramatically the substrate spin life time.…”

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confidence: 84%

Nanoscale Charge Separation Using Chiral Molecules

et al. 2015

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Charge separation is a fundamental process currently being used in a large variety of devices.Typically charge separation requires doped P/N junctions that, at the nano scale, are difficult to form due to the small number of participating atoms. Thus it is not trivial to separate charges at the nanometric scale in a simple flexible way. Recently, studies of electron transfer through organic helical chiral molecules have shown that electron transmission through these molecules is spin dependent at ambient temperatures. Utilizing semiconductor nanocrystals and helical chiral molecules, we created a room-temperature optically activated, thin-layer, chargeseparating nanoscale device. Total efficiency of separation is sensitive to the polarization of the light and could be enhanced by chiral imprinting on the NCs. The fabrication process is simple and uses self-assembly methods that could be applied to a wide variety of nano crystals based devices. From the fundamental point of view the induced chiral charge separation may be relevant for physical and biological processes such as charge separation in photosynthesis.

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confidence: 84%

Nanoscale Charge Separation Using Chiral Molecules

et al. 2015

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“…Among different techniques used to characterize these nanocrystals, those involving magnetic fields become increasingly important. Optical experiments under strong magnetic field enable the investigation of the excitonic fine structure [17][18][19][20][21][22][23]. Electron spin resonance through the measurement of g-factors is a remarkable tool to probe the electron (hole) states in nanocrystals in which the number of electrons is controlled by doping [24][25][26][27] or by the stoichoimetry [28].…”

Section: Introductionmentioning

confidence: 99%

Universal behavior of electron g -factors in semiconductor nanostructures

2017

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We combine analytic developments and numerical tight-binding calculations to study the evolution of the electron g-factors in homogeneous nanostructures of III-V and II-VI semiconductors. We demonstrate that the g-factor can be always written as a sum of bulk and surface terms. The bulk term, the dominant one, just depends on the energy gap of the nanostructure but is otherwise isotropic and independent of size, shape, and dimensionality. At the same time, the magnetic moment density at the origin of the bulk term is anisotropic and strongly dependents on the nanostructure shape. The physical origin of these seemingly contradictory findings is explained by the relation between the spin-orbit-induced currents and the spatial derivatives of the electron envelope wave function. The tight-binding calculations show that the g-factor versus energy gap for spherical nanocrystals can be used as a reference curve. In quantum wells, nanoplatelets, nanorods, and nanowires, the g-factor along the rotational symmetry axis can be predicted from the reference curve with a good accuracy. The g-factors along nonsymmetric axes exhibit more important deviations due to surface contributions but the energy gap remains the main quantity determining their evolution. The importance of surface-induced anisotropies of the g-factors is discussed.

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“…The chirality induced spin selectivity of the chiral organic layer is the key point to the local light‐induced magnetization effect. In the Co/ AHPA‐L/InAs(or CdSe) NCs system, the spin coherence time of NCs exceeds 100 ps, [ 36 ] which is an order of magnitude larger than the transport times through the organic chiral molecules, and the radiation lifetime is in the order of nanoseconds. [ 37 ] Therefore, the charge transfer could occur before exciton recombination, and spin state reversal hardly occurs.…”

Section: Opto‐magnetic Couplings In Organic Chiral Materialsmentioning

confidence: 99%

Organic Chiral Spin‐Optics: The Interaction between Spin and Photon in Organic Chiral Materials

Gao

Qin

2021

Advanced Optical Materials

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Recently, the spin-dependent effects in chiral materials are being intensively explored due to requirements of fundamental research and technological applications. In organic chiral materials, there is a strong electron−phonon coupling, which will affect the magnitude of spin polarization. Moreover, the chirality-generated orbital angular momentum can also affect spin polarization. Thus, the coupling among the electron spin, orbit, lattice, and photon can be effectively enhanced in organic chiral materials, which allows the existence of magneto-chiral dichroism, chirality-induced spin selection effects, magnetic field dependence of circularly polarized light emission and transmission. Recent studies on the electron spin and photon interaction in organic chiral materials are presented and understood here, which provides guidance for the future development and application in organic chiral spin-optics.

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Room-temperature spin coherence in zinc blende CdSe quantum dots studied by time-resolved Faraday ellipticity

Cited by 16 publications

References 33 publications

Nanoscale Charge Separation Using Chiral Molecules

Nanoscale Charge Separation Using Chiral Molecules

Universal behavior of electron g -factors in semiconductor nanostructures

Organic Chiral Spin‐Optics: The Interaction between Spin and Photon in Organic Chiral Materials

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