Dynamics of a Cr spin in a semiconductor quantum dot: Hole-Cr flip-flops and spin-phonon coupling

Lafuente-Sampietro, Alban; Utsumi, H.; Sunaga, M.; Makita, Kenji; Boukari, H.; Kuroda, Shinji; Besombes, L.

doi:10.1103/physrevb.97.155301

Cited by 11 publications

(23 citation statements)

References 45 publications

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“…In analogy with the spin structure of NV centers in diamond, the spin states S z = ±1 of a Cr in a self-assembled QD form a qubit ({+1; −1} spin qubit) strongly coupled to in-plane strain 2 . It was also demonstrated that resonant optical pumping can be used to empty either the S z = +1 or S z = −1 spin states 18,19 . The incorporation of Cr in II-VI semiconductors is therefore a promising route for the realization of hybrid spin-mechanical devices in which the motion of a mechanical oscillator would be coherently coupled to the spin state of a sin-gle atom and probed or coherently controlled through this interaction [13][14][15] .…”

Section: Introductionmentioning

confidence: 99%

Influence of nonequilibrium phonons on the spin dynamics of a single Cr atom

et al. 2020

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We analyse the influence of optically generated non-equilibrium phonons on the spin relaxation and effective spin temperature of an individual Cr atom inserted in a quantum dot. Using a three pulses pump-probe technique, we show that the spin relaxation measured in resonant optical pumping experiments strongly depends on the optical excitation conditions. We observe for an isolated Cr in the dark a heating time shorter than a few hundreds ns after an initial high power non-resonant excitation pulse. A cooling time larger than a few tens of µs, independent on the excitation, is obtained in the same experimental conditions. We show that a tunable spin-lattice coupling dependent on the density of non-equilibrium phonons can explain the observed dynamics. Low energy excitation conditions are found where the Cr spin states Sz=±1 can be efficiently populated by a non-resonant optical excitation, prepared and read-out by resonant optical pumping and conserved in the dark during a few µs. arXiv:1911.07639v1 [cond-mat.mes-hall]

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Section: Introductionmentioning

confidence: 99%

Influence of nonequilibrium phonons on the spin dynamics of a single Cr atom

et al. 2020

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“…The Cr + spin, not studied until now, is characterised by a ferromagnetic coupling with the hole spin and a vanishingly small exchange interaction with the electron spin. This contrast with Cr 2+ where an anti-ferromagnetic exchange interaction with the hole spin was observed 14,40 . The two hole-Cr + ground states with angular momentum M z = ±4 are not sensitive to flip-flops induced by VBM.…”

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confidence: 66%

“…Similarly, Zn anti-site in the barriers of Cr-doped CdTe/ZnTe QDs could be a local source of electron transfer to Cr 2+ by modulation doping. QDs containing an individual iso-electronic Cr 2+ were identified recently 14 . In these dots, the spin S=2 of Cr 2+ is split by a large fine structure term induced by local strain.…”

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A hole-Cr$^{+}$ nano-magnet in a semiconductor quantum dot

Tiwari,

Arino,

Gupta

et al. 2021

Preprint

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We study a new diluted magnetic semiconductor system based on the spin of the ionized acceptor Cr + . We show that the negatively charged Cr + ion, an excited state of the Cr in II-VI semiconductor, can be stable when inserted in a CdTe quantum dot (QD). The Cr + attracts a heavy-hole in the QD and form a stable hole-Cr + complex. Optical probing of this system reveals a ferromagnetic coupling between heavy-holes and Cr + spins. At low temperature, the thermalization on the ground state of the hole-Cr + system with parallel spins prevents the optical recombination of the excess electron on the 3d shell of the atom. We study the dynamics of the nano-magnet formed by the hole-Cr + exchange interaction. The ferromagnetic ground states with Mz=±4 can be controlled by resonant optical pumping and a spin relaxation time in the 20 µs range is obtained at T=4.2 K. This spin memory at zero magnetic field is limited by the interaction with phonons.

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“…To measure the dark-bright exciton coupling [33,34], a longitudinal magnetic field was applied to QD#A. The experimental conditions are the same as those used in Fig.…”

Section: B Magneto-pl Experimentsmentioning

confidence: 99%

Emission properties and temporal coherence of the dark exciton confined in a GaAs/AlxGa1−xAs quantum dot

et al. 2021

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We report measurements of the radiative lifetimes and coherence times of the dark and bright excitons in an asymmetric GaAs/AlGaAs quantum dot. The dots, fabricated by partial infilling of asymmetric in situ etched nanoholes, have low symmetry, which leads to significant dark-bright mixing as demonstrated by dark-bright anticrossing in magnetophotoluminescence spectra. Using an orthogonal excitation-detection waveguiding geometry and quasiresonant excitation, we compare the coherence properties, measured by Michelson interferometry, of the dark and bright exciton from the same dot in the absence of an external magnetic field.

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Dynamics of a Cr spin in a semiconductor quantum dot: Hole-Cr flip-flops and spin-phonon coupling

Cited by 11 publications

References 45 publications

Influence of nonequilibrium phonons on the spin dynamics of a single Cr atom

Influence of nonequilibrium phonons on the spin dynamics of a single Cr atom

A hole-Cr$^{+}$ nano-magnet in a semiconductor quantum dot

Emission properties and temporal coherence of the dark exciton confined in a GaAs/AlxGa1−xAs quantum dot

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