Abstract:Time-and momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser Review of Scientific Instruments 91, 013109 (2020);
“…244 Recently, first spin-resolved measurements with fs time resolution were successful. 245,246 Time-resolved ToF-MM has already reached good visibility in the young and dynamic field of fs-photoemission. Ground-breaking achievements dealt with various aspects in the dynamics of phase transitions (Sec.…”
“…244 Recently, first spin-resolved measurements with fs time resolution were successful. 245,246 Time-resolved ToF-MM has already reached good visibility in the young and dynamic field of fs-photoemission. Ground-breaking achievements dealt with various aspects in the dynamics of phase transitions (Sec.…”
“…From two sets of images at the polarization can be obtained by calculating the asymmetry, and correction by the Sherman function 33 . Further details of the electron spectrometer and spin filter are described in 34 . Figure 2 Spin-integrated photoemission spectrum from the Au layer: the 5d levels (at a binding energy of −4 eV and −6 eV) provide a significantly stronger photoemission yield compared to the valence band.…”
The ultrafast demagnetization effect allows for the generation of femtosecond spin current pulses, which is expected to extend the fields of spin transport and spintronics to the femtosecond time domain. thus far, directly observing the spin polarization induced by spin injection on the femtosecond time scale has not been possible. Herein, we present time-and spin-resolved photoemission results of spin injection from a laser-excited ferromagnet into a thin gold layer. The injected spin polarization is aligned along the magnetization direction of the underlying ferromagnet. Its decay time depends on the thickness of the gold layer, indicating that transport as well as storage of spins are relevant. this capacitive aspect of spin transport may limit the speed of future spintronic devices.
“…Angle-resolved photoemission spectroscopy (ARPES) [1, 2] is arguably the most universal method to probe the electronic band structure of crystalline materials [3,4]. In the past decades there has been a lot of progress resulting in the development of new ARPES-based modalities -soft X-ray, timeresolved [5], spin-resolved [6], and advanced combinations of these [7,8]. At the end of the last century, it was shown [2] that ARPES spectral weight depends on the transition dipole matrix element between the initial Bloch wave and the final states.…”
Dichroic techniques are highly relevant in the field of topological materials, layered systems, and spin-polarized electronic states. Dichroism in angle-resolved photoemission is per se a matrix element effect, which depends on the initial and final states as well as on the perturbation by the light field. Although matrix element effects in ARPES such as dichroism are important for addressing properties of the initial state wave functions, the results can strongly depend on experimental geometry or final state effects. Combining experimental data on bulk WSe2 taken at soft x-ray photon energies with state-of-the-art photoemission calculations, we demonstrate that a dichroic observable called time-reversal dichroism remains unaffected against variation of photon energy, light polarization, and the angle of incidence. The robustness of this matrix element effect indicates a considerable benefit over other dichroic techniques and encourages further experimental and theoretical investigations.
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