Review of Ultrafast Demagnetization After Femtosecond Laser Pulses: A Complex Interaction of Light with Quantum Matter
| Autor: | Michael Haag, Haonan Huang, Weikai Weng, Johan Briones, Nicolas Teeny, Tilmann Kuhn, Manfred Fähnle, B. Y. Mueller, Lifa Zhang, Christian Illg, Theodoros Tsatsoulis |
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| Rok vydání: | 2018 |
| Předmět: |
Physics
Photon Phonon Magnon Physics::Optics 02 engineering and technology General Medicine 021001 nanoscience & nanotechnology Laser 01 natural sciences Electromagnetic radiation law.invention law 0103 physical sciences Femtosecond Quasiparticle Condensed Matter::Strongly Correlated Electrons Atomic physics 010306 general physics 0210 nano-technology Ultrashort pulse |
| Zdroj: | American Journal of Modern Physics. 7:68 |
| ISSN: | 2326-8867 |
| Popis: | When a magnetic film is excited by a femtosecond laser pulse, either with THz or with optical frequencies, then there is at least a partial demagnetization within a few hundred femtoseconds, followed by a remagnetization to the original state on a bit longer time scale. This phenomenon is caused by a complex interaction of light with quantum matter. This paper gives a review of the present knowledge of the underlying physics. It discusses first the situation of a direct change of the magnetization by its interaction with the electromagnetic wave of the laser pulse, which appears during THz laser pulses with small field amplitudes. Then it considers the situation of an indirect change which appears after THz laser pulses with large field amplitudes and after optical laser pulses. In these cases the laser photons primarily excite electrons, with subsequent modifications of their spin-angular momenta by spin-flip scatterings of these electrons at quasiparticles, either at other electrons or at phonons or at magnons. The contributions of these various spin-flip scatterings to demagnetization are investigated. Then the transfer of angular momentum from the electronic spin system to the lattice during ultrafast demagnetization is discussed by describing the lattice vibrations in terms of magnetoelastic spin-phonon modes. Finally, the effect of electronic correlations in the sense of the density-matrix theory is investigated. |
| Databáze: | OpenAIRE |
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