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1.
Spin–charge separation is known to be broken in many physically interesting one‐dimensional (1D) and quasi‐1D systems with spin–orbit interaction because of which spin and charge degrees of freedom are mixed in collective excitations. Mixed spin–charge modes carry an electric charge and therefore can be investigated by electrical means. We explore this possibility by studying the dynamic conductance of a 1D electron system with image‐potential‐induced spin–orbit interaction. The real part of the admittance reveals an oscillatory behavior versus frequency that reflects the collective excitation resonances for both modes at their respective transit frequencies. By analyzing the frequency dependence of the conductance the mode velocities can be found and their spin–charge structure can be determined quantitatively. 相似文献
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G. Bacher H. Schmig M. Scheibner A. Forchel A.A. Maksimov A.V. Chernenko P.S. Dorozhkin V.D. Kulakovskii T. Kennedy T.L. Reinecke 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):37
Self-assembled Cd(Mn)Se/Zn(Mn)Se quantum dots have been investigated by means of spatially and time-resolved magneto-optical spectroscopy. In such quasi zero-dimensional diluted magnetic semiconductors, the exchange interaction couples the spins of optically generated charge carriers with localized magnetic ion spins. We demonstrate that this can be used on the one hand to monitor nanoscale magnetization with a resolution of <100 μB by a purely optical technique and on the other hand to optically manipulate the magnetization in a semiconductor quantum dot. 相似文献
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V. R. Shaginyan V. A. Stephanovich K. G. Popov E. V. Kirichenko S. A. Artamonov 《Annalen der Physik》2016,528(6):483-492
We analyze exciting recent measurements [Phys. Rev. Lett. 114 (2015) 037202] of the magnetization, differential susceptibility and specific heat on one dimensional Heisenberg antiferromagnet Cu(C4H4N2)(NO3)2 (CuPzN) subjected to strong magnetic fields. Using the mapping between magnons (bosons) in CuPzN and fermions, we demonstrate that magnetic field tunes the insulator towards quantum critical point related to so‐called fermion condensation quantum phase transition (FCQPT) at which the resulting fermion effective mass diverges kinematically. We show that the FCQPT concept permits to reveal the scaling behavior of thermodynamic characteristics, describe the experimental results quantitatively, and derive for the first time the (temperature—magnetic field) phase diagram, that contains Landau‐Fermi‐liquid, crossover and non‐Fermi liquid parts, thus resembling that of heavy‐fermion compounds. 相似文献
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High-fidelity quantum sensing of magnon excitations with a single electron spin in quantum dots
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Le-Tian Zhu 《中国物理 B》2022,31(12):120302-120302
Single-electron spins in quantum dots are the leading platform for qubits, while magnons in solids are one of the emerging candidates for quantum technologies. How to manipulate a composite system composed of both systems is an outstanding challenge. Here, we use spin-charge hybridization to effectively couple the single-electron spin state in quantum dots to the cavity and further to the magnons. Through this coupling, quantum dots can entangle and detect magnon states. The detection efficiency can reach 0.94 in a realistic experimental situation. We also demonstrate the electrical tunability of the scheme for various parameters. These results pave a practical pathway for applications of composite systems based on quantum dots and magnons. 相似文献
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Spin-dependent transport in a triple quantum dots superlattice system with a bridge coupling to two leads is studied. There exists an odd-even parity oscillation of spin polarization at the central dot level εc = 0 due to the spin-dependent Fano and Dicke effects induced by the quantum interference and the Rashba spin-orbit interaction. In the case of even numbers of triple quantum dots, the device can be used as a spin switch by tuning the energy difference h between the energies of the central and the lateral dots. These results may be helpful to design and fabricate practical spintronic devices. 相似文献
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Karel Kral 《Czechoslovak Journal of Physics》2006,56(1):33-40
Longitudinal optical phonons have been used to interpret the electronic energy relaxation in quantum dots and at the same
time they served as a reservoir, with which the electronic subsystem is in contact. Such a phonon subsystem is expected to
be passive, namely, in a long-time limit the whole system should be able to achieve such a stationary state, in which statistical
distributions of both subsystems do not change in time. We pay attention to this property of the LO phonon bath. We show the
passivity property of the so far used approximations to electronic transport in quantum dots. Also we show a way how to improve
the passivity of LO phonon bath using canonical Lang-Firsov transformation.
Presented at the X-th Symposium on Suface Physics, Prague, Czech Republic, July 11–15, 2005. 相似文献
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Quantum phase transition and Coulomb blockade effect in triangular quantum dots with interdot capacitive and tunnel couplings
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The quantum phase transition and the electronic transport in a triangular quantum dot system are investigated using the numerical renormalization group method.We concentrate on the interplay between the interdot capacitive coupling V and the interdot tunnel coupling t.For small t,three dots form a local spin doublet.As t increases,due to the competition between V and t,there exist two first-order transitions with phase sequence spin-doublet-magnetic frustration phase-orbital spin singlet.When t is absent,the evolutions of the total charge on the dots and the linear conductance are of the typical Coulomb-blockade features with increasing gate voltage.While for sufficient t,the antiferromagnetic spin correlation between dots is enhanced,and the conductance is strongly suppressed for the bonding state is almost doubly occupied. 相似文献
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Spin-dependent thermoelectric effect and spin battery mechanism in triple quantum dots with Rashba spin-orbital interaction
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We have studied spin-dependent thermoelectric transport through parallel triple quantum dots with Rashba spinorbital interaction(RSOI) embedded in an Aharonov-Bohm interferometer connected symmetrically to leads using nonequilibrium Green's function method in the linear response regime.Under the appropriate configuration of magnetic flux phase and RSOI phase,the spin figure of merit can be enhanced and is even larger than the charge figure of merit.In particular,the charge and spin thermopowers as functions of both the magnetic flux phase and the RSOI phase present quadruple-peak structures in the contour graphs.For some specific configuration of the two phases,the device can provide a mechanism that converts heat into a spin voltage when the charge thermopower vanishes while the spin thermopower is not zero,which is useful in realizing the thermal spin battery and inducing a pure spin current in the device. 相似文献
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We analyze the transport through asymmetric double quantum dots with an inhomogeneous Zeeman splitting in the presence of crossed dc and ac magnetic fields.A strong spin-polarized current can be obtained by changing the dc magnetic field.It is mainly due to the resonant tunnelling.But for the ferromagnetic right electrode,the electron spin resonance also plays an important role in transport.We show that the double quantum dots with three-level mixing under crossed dc and ac magnetic fields can act not only as a bipolar spin filter but also as a spin inverter under suitable conditions. 相似文献
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本文在处理InAs单电子量子点哈密顿模型时,将自旋-轨道(SO)相互作用作为微扰项,计算在Fock-Darwin本征函数下SO相互作用的矩阵元,利用其对能级和波函数的二阶修正,并且考虑新的能级对g因子和有效质量m*的影响,计算得到在声子协助下电子的自旋弛豫率Γ的表达式.给出了InAs量子点中声子协助的电子自旋弛豫率Γ对于限制势频率ω0、温度T、纵向高度z0关键词:
自旋弛豫率
自旋-轨道(SO)相互作用
InAs量子点
Fock-Darwin本征函数 相似文献
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E. S. Freitas Neto A. C. A. Silva S. W. da Silva P. C. Morais J. A. Gmez O. Baffa N. O. Dantas 《Journal of Raman spectroscopy : JRS》2013,44(7):1022-1032
Glass‐embedded Cd1−xCoxS quantum dots (QDs) with mean radius of R ≈ 1.70 nm were successfully synthesized by a novel protocol on the basis of the melting‐nucleation synthesis route and herein investigated by several experimental techniques. Incorporation of Co2+ ions into the QD lattice was evidenced by X‐ray diffraction and magnetic force microscopy results. Optical absorption features with irregular spacing in the ligand field region confirmed that the majority of the incorporated Co2+ ions are under influence of a low‐symmetry crystal field located near to the Cd1−xCoxS QD surface. Electron paramagnetic resonance data confirmed the presence of Co2+ ions in a highly inhomogeneous crystal field environment identified at the interface between the hosting glass matrix (amorphous) and the crystalline QD. The acoustic‐optical phonon coupling in the Cd1−xCoxS QDs (x ≠ 0.000) was directly observed by Raman measurements, which have shown a high‐frequency shoulder of the longitudinal optical phonon peak. This effect is tuned by the size‐dependent sp‐d exchange interaction due to the magnetic doping, causing variations in the coupling between electrons and longitudinal optical phonon. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Spin texturing in a parabolically confined quantum wire with Rashba and Dresselhaus spin–orbit interactions
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In this study, we investigate theoretically the effect of spin–orbit coupling on the energy level spectrum and spin texturing of a quantum wire with a parabolic confining potential subjected to the perpendicular magnetic field. Highly accurate numerical calculations have been carried out using a finite element method. Our results reveal that the interplay between the spin–orbit interaction and the effective magnetic field significantly modifies the band structure, producing additional subband extrema and energy gaps. Competing effects between external field and spin–orbit interactions introduce complex features in spin texturing owing to the couplings in energy subbands. We obtain that spatial modulation of the spin density along the wire width can be considerably modified by the spin–orbit coupling strength, magnetic field and charge carrier concentration. 相似文献
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Decoherence-free spin entanglement generation and purification in nanowire double quantum dots
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We propose a deterministic generation and purification of decoherence-free spin entangled states with singlet-triplet spins in nanowire double quantum dots via resonator-assisted charge manipulation and measurement techniques. Each spin qubit corresponds to two electrons in a double quantum dot in the nanowire, with the singlet and one of the triplets as the decoherence-free qubit states. The logical qubits are immunized against the dominant source of decoherence-dephasing—while the influences of additional errors are shown by numerical simulations. We analyse the performance and stability of all required operations and emphasize that all techniques are feasible in current experimental conditions. 相似文献
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A. M. Alcalde Qu Fanyao G. E. Marques 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):228
We have calculated spin-relaxation rates in parabolic quantum dots due to the phonon modulation of the spin–orbit interaction in the presence of an external magnetic field. Both deformation potential and piezoelectric electron–phonon coupling mechanisms are included within the Pavlov–Firsov spin–phonon Hamiltonian. Our results have demonstrated that, in narrow gap materials, the electron–phonon deformation potential and piezoelectric coupling give comparable contributions to spin-relaxation processes. For large dots, the deformation potential interaction becomes dominant. This behavior is not observed in wide or intermediate gap semiconductors, where the piezoelectric coupling, in general, governs the spin-relaxation processes. We have also demonstrated that spin-relaxation rates are particularly sensitive to the Landé g-factor. 相似文献
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Fangyu Yue Jens W. Tomm Detlef Kruschke Peter Glas 《Laser \u0026amp; Photonics Reviews》2013,7(1):L1-L5
The luminescence behavior of PbS‐quantum dots in glass matrix (PbS:Glass) is investigated. Steady‐state and time‐resolved photoluminescence are applied in a wide range of excitation densities up to pulse energies exceeding 50 µJ/cm2. While perfect linear recombination is observed across four orders of magnitude, an additional radiative recombination mechanism emerges at an excitation density of 1 µ J/cm2 per pulse at 390 nm excitation and increases the external quantum efficiency. The time constant of this process is ∼20–40 ps. It is ascribed to stimulated emission. No hint to any non‐linear non‐radiative processes such as Auger recombination is observed. Thermal effects, however, still set limits. This is encouraging news for PbS:Glass as potential laser material. 相似文献