Quantum kinetic description of spin transfer in diluted magnetic semiconductors

Thurn, Christoph; Axt, Vollrath M.

doi:10.1103/physrevb.85.165203

Cited by 25 publications

(64 citation statements)

References 30 publications

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“…36, where for the conduction band only H 0 and H sd in Eqs. (1) were considered, we seek to obtain a closed set of equations for the reduced carrier and impurity density matrices as well as for the carrier-impurity correlations:…”

Section: B Quantum Kinetic Equations Of Motionmentioning

confidence: 99%

“…To this end we employ a quantum kinetic theory for carrier and impurity density matrices including the carrierimpurity correlations starting from a system Hamiltonian that comprises a kinetic energy term, the magnetic and non-magnetic carrier-impurity interactions as well as the carrier and impurity Zeeman energies. Earlier quantum kinetic studies of the spin dynamics in DMS [25][26][27]36,37 , which only considered the spin-dependent s-d interaction, predicted that in some cases, such as in narrow quantum wells optically excited very close to the band edge 38 , the spin transfer between carriers and impurities cannot be well described by rate equations. Rather, the time evolution of the carrier spin is, in these cases, nonexponential and it can exhibit non-monotonic features such as overshoots.…”

Section: Introductionmentioning

confidence: 99%

“…Here, we find that these non-Markovian effects predicted in the theory of Refs. [25][26][27]36, and 37 are suppressed in the case of the conduction band of a Cd 1−x Mn x Te quantum well when non-magnetic scattering of carriers at the impurities is taken into account. While, in this case, the non-monotonic behavior of the spin dynamics disappears, the quantum kinetic theory predicts quantitative changes in the effective spin transfer rate compared with the Fermi's golden rule value.…”

Section: Introductionmentioning

confidence: 99%

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Influence of nonmagnetic impurity scattering on spin dynamics in diluted magnetic semiconductors

et al. 2017

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The doping of semiconductors with magnetic impurities gives rise not only to a spin-spin interaction between quasi-free carriers and magnetic impurities, but also to a local spin-independent disorder potential for the carriers. Based on a quantum kinetic theory for the carrier and impurity density matrices as well as the magnetic and non-magnetic carrier-impurity correlations, the influence of the non-magnetic scattering potential on the spin dynamics in DMS after optical excitation with circularly polarized light is investigated using the example of Mn-doped CdTe. It is shown that non-Markovian effects, which are predicted in calculations where only the magnetic carrier-impurity interaction is accounted for, can be strongly suppressed in the presence of non-magnetic impurity scattering. This effect can be traced back to a significant redistribution of carriers in k-space which is enabled by the build-up of large carrier-impurity correlation energies. A comparison with the Markov limit of the quantum kinetic theory shows that, in the presence of an external magnetic field parallel to the initial carrier polarization, the asymptotic value of the spin polarization at long times is significantly different in the quantum kinetic and the Markovian calculations. This effect can also be attributed to the formation of strong correlations which invalidates the semiclassical Markovian picture and it is stronger when the non-magnetic carrier-impurity interaction is accounted for. In an external magnetic field perpendicular to the initial carrier spin, the correlations are also responsible for a renormalization of the carrier spin precession frequency. Considering only the magnetic carrier-impurity interaction, a significant renormalization is predicted for a very limited set of material parameters and excitation conditions. Accounting also for the non-magnetic interaction a relevant renormalization of the precession frequency is found to be more ubiquitous.

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Section: B Quantum Kinetic Equations Of Motionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of nonmagnetic impurity scattering on spin dynamics in diluted magnetic semiconductors

et al. 2017

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“…We base our study on a microscopic quantum kinetic theory derived by a correlation expansion scheme 45 that is capable of a non-perturbative description of highly nonequilibrium situations. One aspect of the effects of the carrier-impurity correlations on the spin dynamics has already been found in previous works [46][47][48][49][50] : The correlations mediate the transfer of spins between the carriers and the impurities.…”

Section: Introductionmentioning

confidence: 99%

“…45, where equations of motion have been derived for the electron and impurity density matrices C σ2 σ1k and M n2 n1 as well as their correlations which are defined by…”

Section: Introductionmentioning

confidence: 99%

Nonperturbative correlation effects in diluted magnetic semiconductors

2016

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The effects of carrier-impurity correlations due to a Kondo-like spin-spin interaction in diluted magnetic semiconductors are investigated. These correlations are not only responsible for a transfer of spins between the carriers and the impurities, but also produce non-perturbative effects in the spin dynamics such as renormalization of the precession frequency of the carrier spins, which can reach values of several percent in CdMnTe quantum wells. In two-dimensional systems, the precession frequency renormalization for a single electron spin with defined wave vector shows logarithmic divergences similar to those also known from the Kondo problem in metals. For smooth electron distributions, however, the divergences disappear due to the integrability of the logarithm. A possible dephasing mechanism caused by the wave-vector dependence of the electron spin precession frequencies is found to be of minor importance compared to the spin transfer from the carrier to the impurity system. In the Markov limit of the theory, a quasi-equilibrium expression for the carrier-impurity correlation energy can be deduced indicating the formation of strongly correlated carrier-impurity states for temperatures in the mK range.

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Case study of the validity of truncation schemes of kinetic equations of motion: Few magnetic impurities in a semiconductor quantum ring

Lia,

Tamborenea

2024

Journal of Magnetism and Magnetic Materials

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Quantum kinetic description of spin transfer in diluted magnetic semiconductors

Cited by 25 publications

References 30 publications

Influence of nonmagnetic impurity scattering on spin dynamics in diluted magnetic semiconductors

Influence of nonmagnetic impurity scattering on spin dynamics in diluted magnetic semiconductors

Nonperturbative correlation effects in diluted magnetic semiconductors

Case study of the validity of truncation schemes of kinetic equations of motion: Few magnetic impurities in a semiconductor quantum ring

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