Hole–Nuclear Spin Interaction in Quantum Dots

Eblé, B.; Testelin, C.; Desfonds, Pascal; Bernardot, F.; Balocchi, Andréa; Amand, T.; Miard, A.; Lemaı̂tre, A.; Marie, X.; Chamarro, Maria

doi:10.1103/physrevlett.102.146601

Cited by 157 publications

(207 citation statements)

References 33 publications

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“…23 This slow scale has not yet been experimentally explored for hole spins in QDs. We introduce a new experimental method, working in frequency domain, to measure the hole-spin initialization and relaxation times: the dark-bright time-scanning spectroscopy (DTS).…”

Section: Introductionmentioning

confidence: 99%

“…The hf interaction has been identified as the dominant electron-and hole-spin dephasing source at weak or zero magnetic field and low temperature in QDs, [18][19][20][21][22][23][24][25] leading to a dephasing time in the order of nanoseconds or tens of nanoseconds. Unlike electrons for which the contact term is the predominant contribution of the hf interaction, holes couple more weakly to nuclear spins via the anisotropic dipoledipole term of the hf interaction.…”

Section: Introductionmentioning

confidence: 99%

“…18,20,30 The shorter time scale, in the nanosecond range, has been previously observed for both the electron and hole. 14,22,23 Indeed, in a singly charged QD ensemble, each carrier-precession period is controlled by the hf field of the surrounding nuclei. At the carrier-precession timescale, due to the small variations of the nuclear effective field, it can be considered as frozen, but its dot-to-dot fluctuations induce a carrier spin dephasing and a partial relaxation of the ensemble spin carriers characterized by a dephasing time T e,h .…”

Section: Introductionmentioning

confidence: 99%

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Hole-spin initialization and relaxation times in InAs/GaAs quantum dots

et al. 2011

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We study, at low temperature and zero magnetic field, the hole-spin dynamics in InAs/GaAs quantum dots. We measure the hole-spin relaxation time at a time scale longer than the dephasing time (about ten nanoseconds), imposed by the hole-nuclear hyperfine coupling. We use a pump-probe configuration and compare two experimental techniques based on differential absorption. The first one works in the time domain, and the second one is a new experimental method, the dark-bright time-scanning spectroscopy (DTS), working in the frequency domain. The measured hole-spin relaxation times, using these two techniques, are very similar, in the order of T h N ≈1 μs. It is mainly imposed by the inhomogeneous hole hyperfine coupling in the hole localization volume. The DTS technique allows us also to measure the hole-spin initialization time τ i . The hole spin is initialized by a periodic train of circularly polarized pulses at 76 MHz; we have observed that τ i decreases as the power density increases, and we have measured a minimum value of τ i ≈100 ns in good agreement with a simple model [seeB. Eble, P. Desfonds, F. Fras, F. Bernardot, C. Testelin, M. Chamarro, A. Miard, and A. Lemaître, Phys. Rev. B 81, 045322 (2010)].

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hole-spin initialization and relaxation times in InAs/GaAs quantum dots

et al. 2011

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“…The responsible carriers cannot be the holes in the positive trions as the spin-singlet of the two paired holes in the trion ground state should not be affected by the magnetic field. The spin dephasing time of the residual hole in the QD ground state after the trion recombination was shown to be rather long (14 ns) [20], which can also be excluded as being responsible for the observed short spin lifetime. Hence, it must be the spin precession of the trion electron that has led to the observed Hanle curves.…”

Section: Resultsmentioning

confidence: 99%

The Hanle effect and electron spin polarization in InAs/GaAs quantum dots up to room temperature

et al. 2012

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Abstract. The Hanle effect in InAs/GaAs quantum dots (QDs) is studied under optical orientation as a function of temperature over the range of 150-300 K, with the aim to understand the physical mechanism responsible for the observed sharp increase of electron spin polarization with increasing temperature. The deduced spin lifetime T s of positive trions in the QDs is found to be independent of temperature, and is also insensitive to excitation energy and density. It is argued that the measured T s is mainly determined by the longitudinal spin flip time (T 1 ) and the spin dephasing time (T 2 * ) of the studied QD ensemble, of which both are temperature-independent over the studied temperature range and the latter makes a larger contribution. The observed sharply rising QD spin polarization degree with increasing temperature, on the other hand, is shown to be induced by an increase in spin injection efficiency from the barrier/wetting layer and also by a moderate increase in spin detection efficiency of the QD.PACS numbers: 73.21.La, 78.67.Hc, 72.25.Fe IntroductionSpins in semiconductor quantum dots (QDs) are the subject of extensive current research due to their weak interaction with the solid state environment, resulting in long spin lifetimes and the proposal for their application in spintronics and quantum information technology [1][2][3]. To this end, studies of spin injection and detection are important tasks to advance both our understanding of the relevant physical processes and to guide the design of improved structures for spintronic applications. Spin-related properties of QDs have in past years been investigated extensively, mainly at low temperatures, largely thanks to the availability of modern single-dot optical spectroscopy such as micro-photoluminescence (-PL) and scanning near-field optical microscopy (SNOM) [4][5][6][7][8][9][10]. Unfortunately, applications of these techniques for studies of QDs have been extremely restricted at elevated temperatures due to drastically decreasing emission intensity with increasing temperature. As a result, detailed studies and understanding of spin properties of QDs at temperatures close to room temperature (RT), highly relevant for practical applications, remain very limited.Recently, we reported a dramatic increase in electron spin polarization degree of InAs/GaAs QDs at high temperatures [11]. Polarization values up to 35% in the QD ground state at RT have been found, indicating at least equally high spin detection efficiency. In this work we carry out detailed studies of the Hanle effect [12], i.e. the depolarization effect in a transverse magnetic field, in InAs/GaAs QDs. Our aim is to determine the temperature dependence of the QD electron spin lifetime

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“…[3,4] Additionally, the p-type symmetry of the valence band orbitals causes a weak hyperfine interaction with the lattice nuclei, thus giving rise to decoherence times potentially longer than those of electron spins. [5,6,7,8,9,10,11] This has enabled successful hole spin initialization [12] and coherent control [10,13]. Double quantum dots (DQDs) are a natural extension which should facilitate the use of independent optical transitions for spin preparation, manipulation and readout, [14] as well as the scalability towards multiple qubit architectures.…”

Section: Introductionmentioning

confidence: 99%

Hole spin relaxation in InAs/GaAs quantum dot molecules

Segarra

Climente

Rajadell

et al. 2015

J. Phys.: Condens. Matter

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Abstract. We calculate the spin-orbit induced hole spin relaxation between Zeeman sublevels of vertically stacked InAs quantum dots. The widely used Luttinger-Kohn Hamiltonian, which considers coupling of heavy-and light-holes, reveals that hole spin lifetimes (T 1 ) of molecular states significantly exceed those of single quantum dot states. However, this effect can be overcome when cubic Dresselhaus spin-orbit interaction is strong. Misalignment of the dots along the stacking direction is also found to be an important source of spin relaxation.

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Hole–Nuclear Spin Interaction in Quantum Dots

Cited by 157 publications

References 33 publications

Hole-spin initialization and relaxation times in InAs/GaAs quantum dots

Hole-spin initialization and relaxation times in InAs/GaAs quantum dots

The Hanle effect and electron spin polarization in InAs/GaAs quantum dots up to room temperature

Hole spin relaxation in InAs/GaAs quantum dot molecules

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