Laser-induced ultrafast spin current pulses: a thermodynamic approach

Fognini, Andreas; Michlmayr, Thomas; Vaterlaus, A.; Acremann, Yves

doi:10.1088/1361-648x/aa6a76

Cited by 22 publications

(11 citation statements)

References 66 publications

(79 reference statements)

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“…The sign of the injected spin polarization for delay times fs is consistent with several theoretical predictions 20 – 22 , 36 . However, for delay times fs, several authors observed the injection of minority spins into the gold layer 18 , 21 .…”

Section: Resultssupporting

confidence: 88%

“…The detected majority polarization is in line with the super-diffusive model 13 as the majority electrons travel at a higher velocity. It is also in line with the thermodynamic model 36 as the chemical potential of the majority electrons is affected more by the heating pulse compared to the minority chemical potential. For all measurements, the rise time of the spin polarization is fs.…”

Section: Resultssupporting

confidence: 87%

See 1 more Smart Citation

Detection of femtosecond spin injection into a thin gold layer by time and spin resolved photoemission

Bühlmann

Saerens

Vaterlaus

et al. 2020

Sci Rep

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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.

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Section: Resultssupporting

confidence: 88%

Section: Resultssupporting

confidence: 87%

Detection of femtosecond spin injection into a thin gold layer by time and spin resolved photoemission

Bühlmann

Saerens

Vaterlaus

et al. 2020

Sci Rep

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show abstract

“…First, a femtosecond laser pulse was used to generate spin currents perpendicular to the plane through the ultrafast spin Seebeck effect [ 7 ] and ultrafast superdiffusive spin currents. [ 8–18 ] By means of S2C, the spin current was converted into an in‐plane ultrashort charge current burst giving rise to the emission of THz electromagnetic waves. This scheme has enabled new applications such as spintronic emitters of ultrashort THz electromagnetic pulses.…”

Section: Figurementioning

confidence: 99%

Terahertz Spin‐to‐Charge Conversion by Interfacial Skew Scattering in Metallic Bilayers

et al. 2021

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The efficient conversion of spin to charge transport and vice versa is of major relevance for the detection and generation of spin currents in spin‐based electronics. Interfaces of heterostructures are known to have a marked impact on this process. Here, terahertz (THz) emission spectroscopy is used to study ultrafast spin‐to‐charge‐current conversion (S2C) in about 50 prototypical F|N bilayers consisting of a ferromagnetic layer F (e.g., Ni81Fe19, Co, or Fe) and a nonmagnetic layer N with strong (Pt) or weak (Cu and Al) spin‐orbit coupling. Varying the structure of the F/N interface leads to a drastic change in the amplitude and even inversion of the polarity of the THz charge current. Remarkably, when N is a material with small spin Hall angle, a dominant interface contribution to the ultrafast charge current is found. Its magnitude amounts to as much as about 20% of that found in the F|Pt reference sample. Symmetry arguments and first‐principles calculations strongly suggest that the interfacial S2C arises from skew scattering of spin‐polarized electrons at interface imperfections. The results highlight the potential of skew scattering for interfacial S2C and propose a promising route to enhanced S2C by tailored interfaces at all frequencies from DC to terahertz.

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“…All coupling constants are deduced from experimental results or first-principles considerations. This framework is intrinsically different from recent theoretical investigations of spin current generation [17], which employ a thermodynamic approach that assumes thermal equilibrium. In contrast, our approach is capable of dealing with the highly nonequilibrium scenarios that are expected to occur at such ultrafast time scales.…”

Section: Introductionmentioning

confidence: 98%