Room-temperature optical orientation of the exciton spin in cubic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Ga</mml:mi><mml:mi mathvariant="normal">N</mml:mi><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">Al</mml:mi><mml:mi mathvariant="normal">N</mml:mi></mml:mrow></mml:math>quantum dots

Lagarde, Delphine; Balocchi, Andréa; Carrère, Hélène; Renucci, Pierre; Amand, T.; Marie, X.; Founta, S.; Mariette, H.

doi:10.1103/physrevb.77.041304

Cited by 43 publications

(33 citation statements)

References 28 publications

(77 reference statements)

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“…This high spin purity is in contrast to the initial predictions based on the much heavier effective masses and the smaller bulk spin-orbit splitting of GaN. It is, however, consistent with the long spin relaxation times observed in reference [74]. This surprising behavior can be explained considering the coupling terms in Hamiltonian A.3.…”

Section: Effect Of the Aspect Ratiocontrasting

confidence: 55%

“…However, these built-in fields are negligible in ZB systems and much longer relaxation times are expected. Indeed, Lagarde et al [74] studied the exciton spin dynamics of self-assembled GaN/AlN ZB QDs and showed that the linear polarization persists up to room temperature and the spin relaxation times (exceeding 10 ns) are two or three orders of magnitude longer than in WZ phase.…”

Section: Magnetic-field Modulation Of the Hole Ground State In Cubic mentioning

confidence: 99%

“…Preliminary calculations for a typical-size QD (R = 6 nm and H = 1.5 nm [74,79]) show that the hole ground state has F z = ±3/2 symmetry and a major contribution of the |hh+ component. In order to analyze the VB mixing, the relative weight of each component within the spinor is calculated as c i = figure 3.1(a) shows the results for variable radius and fixed height H = 1.5 nm.…”

Section: Effect Of the Aspect Ratiomentioning

confidence: 99%

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Electronic structure of quantum dots: response to the environment and externally applied fields

Ortí¹

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AgraïmentsLa present Tesi doctoralés el resultat final de quatre anys de treball i esforç en què he tingut la sort de comptar amb el suport de companys, familiars i amics que han compartit amb mi aquesta enriquidora experiència. Sens dubte, el treball que ací es mostra no haguera sigut possible sense la seua ajuda.En primer lloc, voldria agrair a Josep Planelles i Juan Ignacio Climente el haver-me oferit la possibilitat de realitzar aquest projecte de Tesi sota la seua supervisió. Durant tot el temps que he tingut el plaer de treballar amb ells han mostrat un gran interès i una dedicació plena en proporcionar-me la millor formació investigadora tenint sempre present el que seria millor per al meu futur. De la mateixa manera, el meu agraïmentés extensiu a la resta de membres del grup de Química Quàntica Fernando Rajadell, José Luis Movilla, Miquel Royo i Ana Ballester que d'una manera o altra han contribuït a la realització d'aquesta Tesi. En especial vull destacar a Ana B, amb qui vaig tindre la sort de compartir laboratori durant els primers anys de doctorat i que prompte es va convertir en una molt bona amiga. D'altra banda, voldria mostrar també la meua gratitud als amics que han estat al meu costat en el dia a dia durant aquests anys i que han compartit amb mi molts bons moments dintre i fora de la universitat. En concret vull destacar a Ana M, David, Erica, Neus, Paula i, com no, a chéritounet Loucou. A més, cal mencionar a tots els membres del Departament de Química Física i Analítica, especialment a Merche per la seva predisposició a ajudar-me amb tota la paperassa i els tràmits burocràtics. Done també les gràcies a Sergio E. Ulloa per donar-me l'oportunitat de realitzar una estada breu en el seu grup de recerca en la Universitat d'Ohio (Estats Units), així com a tots els membres del grup per la seua acollida.Finalment, voldria agrair de cor als meus pares el suport i la confiança incondicionals que m'han donat durant tota la meua vida. Perquè són els principals responsables de que haja arribat fins ací, els dedique aquesta Tesi.

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Section: Effect Of the Aspect Ratiocontrasting

confidence: 55%

Section: Magnetic-field Modulation Of the Hole Ground State In Cubic mentioning

confidence: 99%

Section: Effect Of the Aspect Ratiomentioning

confidence: 99%

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Electronic structure of quantum dots: response to the environment and externally applied fields

Ortí¹

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“…[3,9] The ground state has F z = 3/2 symmetry, with a largely dominant |hh + component. [31] Yet, the minor components are important in determining the optical polarization and the hole spin dynamics.…”

Section: Effect Of the Aspect Ratiomentioning

confidence: 99%

“…[6] Lagarde et al showed that, as a consequence, the optical orientation in cubic structures is robust even at room temperature, with exciton spin lifetimes exceeding 10 ns. [9] These results hold promise for both optoelectronic and spintronic applications of cubic GaN/AlN QDs, and have triggered an increasing number of works investigating their properties. [2,10,11,12,13] An important aspect to understand such properties is the valence band mixing, which is known to underlie the optical polarization [13,14] and the exciton spin dynamics.…”

Section: Introductionmentioning

confidence: 99%

Valence band mixing of cubic GaN/AlN quantum dots

Segarra¹,

Climente²,

Planelles³

2012

J. Phys.: Condens. Matter

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Abstract.We study the spin purity of the hole ground state in nearly axially symmetric GaN/AlN quantum dots (QDs). To this end, we develop a six-band Burt-Foreman Hamiltonian describing the valence band structure of zinc-blende nanostructures with cylindrical symmetry, and calculate the effects of eccentricity variationally. We show that that the aspect ratio is a key factor for spin purity. In typical QDs with small aspect ratio the ground state is essentially a heavy hole (HH) whose spin purity is even higher than that of InGaAs QDs of similar size. When the aspect ratio increases, mixing with light-hole (LH) and split-off (SO) subbands becomes important and, additionally, the ground state becomes sensitive to QD anisotropy, which further enhances the mixing. We finally show that despite the large GaN hole effective mass, an efficient magnetic modulation is feasible in QDs with aspect ratio ∼ 1, which can be used to modify the ground state symmetry and hence the optical spectrum properties.

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Exciton‐related optical properties in zinc‐blende GaN/InGaN quantum wells under hydrostatic pressure

Duque

Morales

2015

Physica Status Solidi (b)

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The exciton‐related optical absorption in zinc‐blende InGaN/GaN single quantum wells (QW) under hydrostatic pressure is studied. The energy states in the system are calculated within the effective mass approximation and a variational scheme, taking into account the effects of applied hydrostatic pressure an static electric field. The optical response is calculated in the framework of the two‐level model and the rotating wave approximation. The results are given as functions of the In molar fraction, the QW width, the hydrostatic pressure, and the electric field strength. It is found that a significant exciton‐related nonlinear absorption can be achieved in the range of photon energies around 100meV, for the kind of structures under study.

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Room-temperature optical orientation of the exciton spin in cubicGaN∕AlNquantum dots

Cited by 43 publications

References 28 publications

Electronic structure of quantum dots: response to the environment and externally applied fields

Electronic structure of quantum dots: response to the environment and externally applied fields

Valence band mixing of cubic GaN/AlN quantum dots

Exciton‐related optical properties in zinc‐blende GaN/InGaN quantum wells under hydrostatic pressure

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