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Nonexponential spin decay in a quantum kinetic description of the D'yakonov-Perel' mechanism mediated by impurity scattering

Title data

Cosacchi, Michael ; Cygorek, Moritz ; Ungar, Florian ; Axt, Vollrath M.:
Nonexponential spin decay in a quantum kinetic description of the D'yakonov-Perel' mechanism mediated by impurity scattering.
In: Physical Review B. Vol. 95 (2017) Issue 19 . - Art.Nr. 195313, 12 S..
ISSN 0163-1829
DOI: https://doi.org/10.1103/PhysRevB.95.195313

Project information

Project financing: Deutsche Forschungsgemeinschaft

Abstract in another language

The electron spin dynamics in an optically excited narrow quantum well is studied, where the electron spins precess in a k-dependent magnetic field, while the electrons scatter at localized impurities. For the resulting spin decay, which is commonly known as the D'yakonov-Perel' mechansim, analytical expressions in the strong- and weak-scattering limits are available. It is found by the numerical solution of quantum kinetic equations in a broad range of parameters that, in situations that are typically relevant for ultrafast optical experiments, the dynamics of the total spin polarization significantly deviates from the pertinent analytical results. This is attributed to the broad spectral width of the optically excited spin-polarized electron distribution, which gives rise to a spin dephasing due to inhomogeneous broadening. Furthermore, it is found that the decay of the spin polarization need not be exponential. The notion of a spin decay time becomes ambiguous and different definitions of spin decay times can lead to different outcomes. The long-term dynamics of the decay of the spin polarization is even dominated by an algebraically decaying component. These findings highlight the importance of the effects of the broad spectral distribution of optically excited carriers in ultrashort magneto-optical experiments.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: electron spin dynamics; spintronics; quantum kinetics; density matrix theory; D'yakonov-Perel' mechansim; ultrafast dynamics; optically excited spin-polarized electrons; non-exponential spin decay; impurity scattering
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III > Chair Theoretical Physics III - Univ.-Prof. Dr. Martin Axt
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 06 Nov 2017 12:56
Last Modified: 06 Nov 2017 12:56
URI: https://eref.uni-bayreuth.de/id/eprint/40302