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Snelling, M. J.; Flinn, G.P.; Plaut, A. S.; Harley, R. T.; Tropper, A.C.; Eccleston, Richard; Phillips, Chris C.

doi:10.1103/physrevb.44.11345

Cited by 216 publications

(126 citation statements)

References 28 publications

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“…The value of g xx is negative for quantum wells that are wider than ≈7 nm, as is the case for the quantum wells investigated in this report. 23,24 The magnitude of the off diagonal element is given as 13…”

Section: Origin Of G * Anisotropymentioning

confidence: 99%

Effect of symmetry reduction on the spin dynamics of (001)-oriented GaAs quantum wells

et al. 2013

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Spin quantum beat spectroscopy is employed to investigate the in-plane anisotropy of the spin dynamics in (001) GaAs/AlGaAs quantum wells induced by an external electric field. This technique allows the anisotropy of the spin relaxation rate s and the electron Landé g factor g * to be measured simultaneously. The measurements are compared to similar data from (001) GaAs/AlGaAs quantum wells with applied shear strain and asymmetric barrier growth. All of these operations act to reduce the symmetry compared to that of a symmetric (001) quantum well in an identical manner (D 2d → C 2v ). However, by looking at the anisotropy of both s and g * simultaneously we show that the microscopic actions of these symmetry breaking operations are very different. The experiments attest that although symmetry arguments are a very useful tool to identify the allowed spin dependent properties of a material system, only a microscopic approach reveals if allowed anisotropies will manifest.

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Section: Origin Of G * Anisotropymentioning

confidence: 99%

Effect of symmetry reduction on the spin dynamics of (001)-oriented GaAs quantum wells

et al. 2013

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“…Non-linearities of its B-dependence are well known for systems of higher dimensionality such as quantum wells. [16] A contribution arising from possible field-dependence of the electronic g-factor is likely to be neglected, and the non-linearities mostly originate from heavy hole-light hole mixing which varies with magnetic field. [17] Even though a quantitative understanding can be obtained only on base of detailed band structure calculations [18] (which are beyond the scope of this paper), the spin-splitting thereby permits to take insight into valence band mixing.…”

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Ground-state emission from a singleInAs∕GaAsself-assembled quantum dot structure in ultrahigh magnetic fields

et al. 2006

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We report on the magnetic field dispersion of the exciton spin-splitting and diamagnetic shift in single InAs/GaAs quantum dots (QDs) and dot molecules (QDMs) up to B = 28 T. Only for systems with strong geometric confinement, the dispersions can be well described by simple field dependencies, while for dots with weaker confinement considerable deviations are observed: most importantly, in the high field limit the spin-splitting shows a non-linear dependence on B, clearly indicating light hole admixtures to the valence band ground state.

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“…Currents through the dot, IQD, and through the QPC, IQP C , are measured as a function of applied bias voltage, VSD = (µS − µD)/e and VQD = (µQ − µD)/e respectively. Factors which can influence the magnetic field dependence of the g-factor include: (1) extension of the electron wavefunction into the Al 0.3 Ga 0.7 As region, where g = +0.4 [21,22], (2) thermal nuclear polarization, which decreases the effective magnetic field through the hyperfine interaction [23], (3) dynamic nuclear polarization due to electron-nuclear flip-flop processes in the dot, which enhances the effective magnetic field [23], and (4) the nonparabolicity of the GaAs conduction band [21]. More experiments are needed to separate these effects, which is outside the scope of this Letter.…”

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Zeeman Energy and Spin Relaxation in a One-Electron Quantum Dot

et al. 2003

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We have measured the relaxation time, T1, of the spin of a single electron confined in a semiconductor quantum dot (a proposed quantum bit). In a magnetic field, applied parallel to the two-dimensional electron gas in which the quantum dot is defined, Zeeman splitting of the orbital states is directly observed by measurements of electron transport through the dot. By applying short voltage pulses, we can populate the excited spin state with one electron and monitor relaxation of the spin. We find a lower bound on T1 of 50 µs at 7.5 T, only limited by our signal-to-noise ratio. A continuous measurement of the charge on the dot has no observable effect on the spin relaxation.PACS numbers: 73.63. Kv, 03.67.Lx, 73.23.Hk The spin of an electron confined in a semiconductor quantum dot (QD) is a promising candidate for a scalable quantum bit [1,2]. The electron spin states in QDs are expected to be very stable, because the zerodimensionality of the electron states in QDs leads to a significant suppression of the most effective 2D spin-flip mechanisms [3]. Recent electrical transport measurements of relaxation between spin triplet and singlet states of two electrons, confined in a pillar etched from a GaAs double-barrier heterostructure ("vertical" QD), support this prediction (relaxation time > 200 µs at T ≤ 0.5 K) [4]. However, the triplet-to-singlet transition, in which the total spin quantum number S is changed from 1 to 0, is forbidden by a selection rule (∆S=0) that does not hinder relaxation between Zeeman sublevels (which conserves S ). Therefore, measurements on a single electron spin are needed in order to determine the relaxation time of the proposed qubit.Relaxation between Zeeman sublevels in closed GaAs QDs is expected to be dominated by hyperfine interaction with the nuclei at magnetic fields below 0.5 T [5] and by spin-orbit interaction at higher fields [6]. At 1 T, theory predicts a T 1 of 1 ms in GaAs [6]; at fields above a few Tesla, needed to resolve the Zeeman splitting in transport measurements, no quantitative estimates for T 1 exist.For comparison, in n-doped self-assembled InAs QDs containing one resident electron, pump-probe photoluminescence measurements gave a single-electron spin relaxation time of 15 ns (at B=0 T, T = 10 K) [7]. In undoped self-assembled InAs QDs, the exciton polarization is frozen throughout the exciton lifetime, giving a relaxation time >20 ns [8].Electrical measurements of the single-electron spin relaxation time have up to now remained elusive. In vertical QDs, where electrical measurements on a single electron were reported almost a decade ago [9], it has been difficult to directly resolve the Zeeman splitting of orbitals [10]. Recently, the one-electron regime was also reached in single [11] and double lateral GaAs QDs [12], which are formed electrostatically within a twodimensional electron gas (2DEG) by means of surface gates.In this Letter we study the spin states of a one-electron lateral QD directly, by performing energy spectroscopy and relaxation measurement...

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Magneticgfactor of electrons in GaAs/AlxGa1−

Cited by 216 publications

References 28 publications

Effect of symmetry reduction on the spin dynamics of (001)-oriented GaAs quantum wells

Effect of symmetry reduction on the spin dynamics of (001)-oriented GaAs quantum wells

Ground-state emission from a singleInAs∕GaAsself-assembled quantum dot structure in ultrahigh magnetic fields

Zeeman Energy and Spin Relaxation in a One-Electron Quantum Dot

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