Spin-Dependent Electron Dynamics in Front of a Ferromagnetic Surface

Schmidt, Anke B.; Pickel, M.; Wiemhöfer, Martin; Donath, M.; Weinelt, Martin

doi:10.1103/physrevlett.95.107402

Cited by 69 publications

(55 citation statements)

References 35 publications

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“…However, if the pulses are temporarily separated, then an excited electron from the first pulse is able to absorb a photon from the second pulse only as long as the inelastic lifetime of the intermediate state exceeds the delay or if the normally unoccupied electronic state is refilled by a secondary electron. Because of the precise measurement of the time delay between the two pulses, this technique allows analysis of relaxation times which are considerably shorter than the laser pulse duration; see, e.g., Schmidt et al ͑2005͒.…”

Section: Ultraviolet Probe and Spin-polarized Electronsmentioning

confidence: 99%

Ultrafast optical manipulation of magnetic order

2010

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The interaction of subpicosecond laser pulses with magnetically ordered materials has developed into a fascinating research topic in modern magnetism. From the discovery of subpicosecond demagnetization over a decade ago to the recent demonstration of magnetization reversal by a single 40 fs laser pulse, the manipulation of magnetic order by ultrashort laser pulses has become a fundamentally challenging topic with a potentially high impact for future spintronics, data storage and manipulation, and quantum computation. Understanding the underlying mechanisms implies understanding the interaction of photons with charges, spins, and lattice, and the angular momentum transfer between them. This paper will review the progress in this field of laser manipulation of magnetic order in a systematic way. Starting with a historical introduction, the interaction of light with magnetically ordered matter is discussed. By investigating metals, semiconductors, and dielectrics, the roles of ͑nearly͒ free electrons, charge redistributions, and spin-orbit and spin-lattice interactions can partly be separated, and effects due to heating can be distinguished from those that are not. It will be shown that there is a fundamental distinction between processes that involve the actual absorption of photons and those that do not. It turns out that for the latter, the polarization of light plays an essential role in the manipulation of the magnetic moments at the femtosecond time scale. Thus, circularly and linearly polarized pulses are shown to act as strong transient magnetic field pulses originating from the nonabsorptive inverse Faraday and inverse Cotton-Mouton effects, respectively. The recent progress in the understanding of magneto-optical effects on the femtosecond time scale together with the mentioned inverse, optomagnetic effects promises a bright future for this field of ultrafast optical manipulation of magnetic order or femtomagnetism.

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Section: Ultraviolet Probe and Spin-polarized Electronsmentioning

confidence: 99%

Ultrafast optical manipulation of magnetic order

2010

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“…The necessity for two-photon absorption opens the possibility to study the dynamics of the intermediate-state occupation on a femtosecond time scale by two-photon pump-probe experiments, where probe laser pulses are subject to a controlled femtosecond delay with respect to pump pulses. Hot electron dynamics on semiconductor [10] and metal surfaces [8,11,36] has been investigated by this method, including its spin dependence [12,13]. The most comprehensive studies have been carried out on image-potential states on metal surfaces, i.e.…”

Section: Introductionmentioning

confidence: 99%

Photoemission momentum mapping and wave function analysis of surface and bulk states on flat Cu(111) and stepped Cu(443) surfaces: A two-photon photoemission study

et al. 2008

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(2008). Photoemission momentum mapping and wave function analysis of surface and bulk states on flat Cu(111) and stepped Cu(443) surfaces: A two-photon photoemission study. Physical Review B, 77(8) AbstractAccurate momentum mapping of bulk and surface electronic states by angle-resolved two-photon photoemission is demonstrated on Cu(111) and one of its vicinal surfaces, Cu(443), using laser light of 3.08 eV photon energy for excitation. The surface state dispersion was found to exhibit dispersion corresponding to the periodic arrangement of terraces and monatomic steps on Cu(443).Polarization dependent data suggest that the state consists of out-of-plane p z -orbitals like on the flat (111) copper surface, mixed with in-plane p-orbitals at the step edges. The results corroborate the general model that on vicinals with an average terrace size below a given length, surface states behave as de-localized states, and that the corresponding wavefunctions extent over several terraces.Moreover, the low electron kinetic energies encountered in such angle-resolved experiments with laser excitation translate into high momentum resolution. Maps of the Fermi surface taken from the vicinal surface are found to be in excellent agreement with conventional photoemission data and density-functional calculations. This proves that multi-photon photoemission can be used like direct one-photon photoemission as initial state spectroscopy with high energy and momentum resolution provided that no real intermediate states are involved in the excitation process.

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“…These spinresolved investigations may provide a basis for the coherent manipulation and probing of the spin dynamics of excited electrons at nonmagnetic surfaces via multiphoton photoemission. Such investigations can complement studies of spindependent electron dynamics at magnetic surfaces [57].…”

Section: Spin-polarized Multiphoton Photoemissionmentioning

confidence: 99%

Higher Order Photoemission from Metal Surfaces

Winkelmann

Chiang

Bisio

et al. 2010

Dynamics at Solid State Surfaces and Interfaces

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Photoemission spectroscopy (PES) is a widely employed method for mapping the electronic structure of solids [1,2]. In the simplest picture, the incident radiation induces transitions of electrons from occupied to unoccupied single-particle states separated by the photon energy. By invoking the laws of energy and momentum conservation, the photoemission process can be applied to map the occupied band structure of solids by detecting the photoelectrons in final states above the vacuum barrier.A generalization of the linear one-photon photoelectric effect can be realized by nonlinear multiphoton processes induced by ultrashort laser pulses of high intensity, where the occupied initial states, the unoccupied intermediate states, and the coupling between them play a central role. The unique power of these effects stems from the fact that the dynamical processes in the intermediate excited states become directly accessible in the time domain when using delayed excitation pulses. Especially the technique of time-resolved two-photon photoemission (2PPE) has been used to gain information on the decay rates of electronic populations and their dephasing times [3][4][5].Compared to 2PPE, higher order multiphoton photoemission processes (mPPE) in solids, which can extend the energy range of the studied unoccupied states and provide further information on photoexcitation processes, have received only little attention. This is mainly because their observation requires very intense optical fields and their considerably reduced photoelectron yields can be overwhelmed by space charge effects from the lower order processes [6][7][8][9][10][11][12][13][14][15]. Moreover, nonphotoelectric effect emission through the surface plasmon excitation and possibly tunneling, leading to ponderomotive acceleration of photoelectrons up to 0.4 keV energy [9,16], has been reported with comparatively low external fields. Therefore, the mechanisms for high-order photoelectric excitations at solid surfaces, in particular to what extent they are governed by the band structure of metals, are largely unexplored.

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Spin-Dependent Electron Dynamics in Front of a Ferromagnetic Surface

Cited by 69 publications

References 35 publications

Ultrafast optical manipulation of magnetic order

Ultrafast optical manipulation of magnetic order

Photoemission momentum mapping and wave function analysis of surface and bulk states on flat Cu(111) and stepped Cu(443) surfaces: A two-photon photoemission study

Higher Order Photoemission from Metal Surfaces

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