Competing Spin Transfer and Dissipation at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>Co</mml:mi><mml:mo>/</mml:mo><mml:mi>Cu</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mn>001</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math>Interfaces on Femtosecond Timescales

Chen, J.; Bovensiepen, Uwe; Eschenlohr, A.; Müller, T.; Elliott, Peter; Gross, E. K. U.; Dewhurst, J. K.; Sharma, S.

doi:10.1103/physrevlett.122.067202

Cited by 71 publications

(75 citation statements)

References 52 publications

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“…How can we understand a sub-20-fs demagnetization time? Very recently, comparably fast demagnetization times down to the sub-20 fs regime were reported even for NIR laser-induced demagnetization in Co/Cu [42] and Ni/Pt [43] and attributed to spin transfer across chemical interfaces. Both studies indicate that three different processes promote demagnetization occurring on subsequent time scales, namely coherent spin transfer and back transfer from ferromagnetic to paramagnetic lattice sites for 𝑡 < 20 fs, referred to as optically induced coherent spin transfer (OISTR) in Ref.…”

Section: Discussionmentioning

confidence: 99%

Ultrafast Demagnetization Excited by Extreme Ultraviolet Light From a Free-Electron Laser

Philippi-Kobs

Müller

Berntsen

et al. 2021

Preprint

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Ultrashort and intense extreme ultraviolet (XUV) and X-ray pulses readily available at free-electron lasers (FELs) enable studying non-linear light−matter interactions on femtosecond timescales. Here, we report on the non-linear fluence dependence of magnetic scattering of Co/Pt multilayers, using FERMI FEL’s 70-fs-long single and double XUV pulses, the latter with a temporal separation of 200 fs, with a photon energy slightly detuned to the Co M2,3 absorption edge. We observe a quenching in magnetic scattering that sets-in already in the non-destructive fluence regime of a few mJ/cm² typically used for FEL-probe experiments on magnetic materials. Calculations of the transient electronic structure in tandem with a phenomenological modeling of the experimental data by means of ultrafast demagnetization unambiguously show that XUV-radiation-induced demagnetization is the dominant mechanism for the quenching in the investigated fluence regime of <50 mJ/cm², while light-induced changes of the electronic core levels are predicted to additionally occur at higher fluences. The modeling of the data further indicates that the demagnetization proceeds on the sub-20-fs timescale. This ultrashort timescale is consistent with non-coherent models for ultrafast demagnetization, considering the sub-femtosecond lifetime of hot electrons with energies of a few 10 eV generated by the XUV radiation.

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Section: Discussionmentioning

confidence: 99%

Ultrafast Demagnetization Excited by Extreme Ultraviolet Light From a Free-Electron Laser

Philippi-Kobs

Müller

Berntsen

et al. 2021

Preprint

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“…The authors of this theoretical study also predicted that the spin-selective charge transfer between distinct sites can lead to a metamagnetic phase transition, switching the magnetic order from an antiferromagnetic to a transient ferromagnetic alignment. In the last two years, a number of experiments demonstrated signatures of OISTR, both in the optical [13,14] as well as in the extreme ultraviolet (XUV) [15][16][17][18] spectral range. The latter experiments were carried out with high harmonic generation (HHG) sources and exploited the element specificity of resonant core-to-valence state transitions.…”

Section: Introductionmentioning

confidence: 99%

Element-Specific Magnetization Dynamics of Complex Magnetic Systems Probed by Ultrafast Magneto-Optical Spectroscopy

et al. 2020

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The vision to manipulate and control magnetism with light is driven on the one hand by fundamental questions of direct and indirect photon-spin interactions, and on the other hand by the necessity to cope with ever growing data volumes, requiring radically new approaches on how to write, read and process information. Here, we present two complementary experimental geometries to access the element-specific magnetization dynamics of complex magnetic systems via ultrafast magneto-optical spectroscopy in the extreme ultraviolet spectral range. First, we employ linearly polarized radiation of a free electron laser facility to demonstrate decoupled dynamics of the two sublattices of an FeGd alloy, a prerequisite for all-optical magnetization switching. Second, we use circularly polarized radiation generated in a laboratory-based high harmonic generation setup to show optical inter-site spin transfer in a CoPt alloy, a mechanism which only very recently has been predicted to mediate ultrafast metamagnetic phase transitions.

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“…ltrafast magnetism belongs to one of the most active fields in solid-state physics with frequent discoveries of new fundamental microscopic phenomena. Prominent examples include all-optical magnetization switching mediated by a transient ferromagnetic state 1,2 , control of antiferromagnetic order [3][4][5][6][7] and transfer of angular momentum via terahertz spin currents [8][9][10][11][12][13] . Very recently it was shown theoretically, that in multi-component magnetic systems laser-driven optical transitions can induce a spin-selective charge flow between sub-lattices causing significant magnetization changes, including switching from antiferromagnetic to ferromagnetic order [14][15][16][17][18] .…”

mentioning

confidence: 99%

Optical inter-site spin transfer probed by energy and spin-resolved transient absorption spectroscopy

et al. 2020

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Optically driven spin transport is the fastest and most efficient process to manipulate macroscopic magnetization as it does not rely on secondary mechanisms to dissipate angular momentum. In the present work, we show that such an optical inter-site spin transfer (OISTR) from Pt to Co emerges as a dominant mechanism governing the ultrafast magnetization dynamics of a CoPt alloy. To demonstrate this, we perform a joint theoretical and experimental investigation to determine the transient changes of the helicity dependent absorption in the extreme ultraviolet spectral range. We show that the helicity dependent absorption is directly related to changes of the transient spin-split density of states, allowing us to link the origin of OISTR to the available minority states above the Fermi level. This makes OISTR a general phenomenon in optical manipulation of multi-component magnetic systems.

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Competing Spin Transfer and Dissipation atCo/Cu(001)Interfaces on Femtosecond Timescales

Cited by 71 publications

References 52 publications

Ultrafast Demagnetization Excited by Extreme Ultraviolet Light From a Free-Electron Laser

Ultrafast Demagnetization Excited by Extreme Ultraviolet Light From a Free-Electron Laser

Element-Specific Magnetization Dynamics of Complex Magnetic Systems Probed by Ultrafast Magneto-Optical Spectroscopy

Optical inter-site spin transfer probed by energy and spin-resolved transient absorption spectroscopy

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