Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau–Lifschitz–Gilbert equation
The real-time dynamics of a classical spin in an external magnetic field and local exchange coupled to an extended one-dimensional system of non-interacting conduction electrons is studied numerically. Retardation effects in the coupled electron-spin dynamics are shown to be the source for the relax...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2015-01-01
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| Series: | New Journal of Physics |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1367-2630/17/11/113058 |
| _version_ | 1797751037963010048 |
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| author | Mohammad Sayad Michael Potthoff |
| author_facet | Mohammad Sayad Michael Potthoff |
| author_sort | Mohammad Sayad |
| collection | DOAJ |
| description | The real-time dynamics of a classical spin in an external magnetic field and local exchange coupled to an extended one-dimensional system of non-interacting conduction electrons is studied numerically. Retardation effects in the coupled electron-spin dynamics are shown to be the source for the relaxation of the spin in the magnetic field. Total energy and spin is conserved in the non-adiabatic process. Approaching the new local ground state is therefore accompanied by the emission of dispersive wave packets of excitations carrying energy and spin and propagating through the lattice with Fermi velocity. While the spin dynamics in the regime of strong exchange coupling J is rather complex and governed by an emergent new time scale, the motion of the spin for weak J is regular and qualitatively well described by the Landau–Lifschitz–Gilbert (LLG) equation. Quantitatively, however, the full quantum–classical hybrid dynamics differs from the LLG approach. This is understood as a breakdown of weak-coupling perturbation theory in J in the course of time. Furthermore, it is shown that the concept of the Gilbert damping parameter is ill-defined for the case of a one-dimensional system. |
| first_indexed | 2024-03-12T16:42:36Z |
| format | Article |
| id | doaj.art-849aaeffb5664c28864c5cc904bd8640 |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:42:36Z |
| publishDate | 2015-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-849aaeffb5664c28864c5cc904bd86402023-08-08T14:24:14ZengIOP PublishingNew Journal of Physics1367-26302015-01-01171111305810.1088/1367-2630/17/11/113058Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau–Lifschitz–Gilbert equationMohammad Sayad0Michael Potthoff1I. Institut für Theoretische Physik, Universität Hamburg , Jungiusstraße 9, D-20355 Hamburg, GermanyI. Institut für Theoretische Physik, Universität Hamburg , Jungiusstraße 9, D-20355 Hamburg, GermanyThe real-time dynamics of a classical spin in an external magnetic field and local exchange coupled to an extended one-dimensional system of non-interacting conduction electrons is studied numerically. Retardation effects in the coupled electron-spin dynamics are shown to be the source for the relaxation of the spin in the magnetic field. Total energy and spin is conserved in the non-adiabatic process. Approaching the new local ground state is therefore accompanied by the emission of dispersive wave packets of excitations carrying energy and spin and propagating through the lattice with Fermi velocity. While the spin dynamics in the regime of strong exchange coupling J is rather complex and governed by an emergent new time scale, the motion of the spin for weak J is regular and qualitatively well described by the Landau–Lifschitz–Gilbert (LLG) equation. Quantitatively, however, the full quantum–classical hybrid dynamics differs from the LLG approach. This is understood as a breakdown of weak-coupling perturbation theory in J in the course of time. Furthermore, it is shown that the concept of the Gilbert damping parameter is ill-defined for the case of a one-dimensional system.https://doi.org/10.1088/1367-2630/17/11/113058spin dynamicselectronic structurehybrid modelsLandau–Lifshitz–Gilbert equation75.78.-n75.78.Jp |
| spellingShingle | Mohammad Sayad Michael Potthoff Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau–Lifschitz–Gilbert equation New Journal of Physics spin dynamics electronic structure hybrid models Landau–Lifshitz–Gilbert equation 75.78.-n 75.78.Jp |
| title | Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau–Lifschitz–Gilbert equation |
| title_full | Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau–Lifschitz–Gilbert equation |
| title_fullStr | Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau–Lifschitz–Gilbert equation |
| title_full_unstemmed | Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau–Lifschitz–Gilbert equation |
| title_short | Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau–Lifschitz–Gilbert equation |
| title_sort | spin dynamics and relaxation in the classical spin kondo impurity model beyond the landau lifschitz gilbert equation |
| topic | spin dynamics electronic structure hybrid models Landau–Lifshitz–Gilbert equation 75.78.-n 75.78.Jp |
| url | https://doi.org/10.1088/1367-2630/17/11/113058 |
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