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- Eschenlohr, A., et al.
(författare)
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Ultrafast spin transport as key to femtosecond demagnetization
- 2013
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Ingår i: Nature Materials. - 1476-1122 .- 1476-4660. ; 12:4, s. 332-336
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Tidskriftsartikel (refereegranskat)abstract
- Irradiating a ferromagnet with a femtosecond laser pulse is known to induce an ultrafast demagnetization within a few hundred femtoseconds. Here we demonstrate that direct laser irradiation is in fact not essential for ultrafast demagnetization, and that electron cascades caused by hot electron currents accomplish it very efficiently. We optically excite a Au/Ni layered structure in which the 30 nm Au capping layer absorbs the incident laser pump pulse and subsequently use the X-ray magnetic circular dichroism technique to probe the femtosecond demagnetization of the adjacent 15 nm Ni layer. A demagnetization effect corresponding to the scenario in which the laser directly excites the Ni film is observed, but with a slight temporal delay. We explain this unexpected observation by means of the demagnetizing effect of a superdiffusive current of non-equilibrium, non-spin-polarized electrons generated in the Au layer.
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| 3. |
- Öhrwall, Gunnar, et al.
(författare)
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A new energy and angle resolving electron spectrometer - First results
- 2011
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 183:1-3, s. 125-131
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Tidskriftsartikel (refereegranskat)abstract
- A new energy and angle resolved analyzer for photoelectron spectroscopy is described. This analyzer is based on combining an advanced focusing electron lens system with time-of-flight measurements. A position sensitive detector gives time and position for the electron events. From this information the kinetic energy and start direction are obtained through a transformation procedure, giving both a large luminosity and a very high energy resolution. The instrument analyses the angles of emission of the electrons in a cone with 30 degrees opening angle and simulations show that extremely high energy and angular resolution can be achieved simultaneously. We report the first results from this instrument, obtained at the PM-3 beam line at BESSY (Berlin, Germany). This analyzer opens up new possibilities for angular resolved electron spectroscopy, band-mapping and other applications.
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