Transition from Optically Excited to Intrinsic Spin Polarization in WSe$_2$
Authors:
Sebastian Hedwig,
Gregor Zinke,
Jürgen Braun,
Benito Arnoldi,
Aki Pulkkinen,
Ján Minár,
Hubert Ebert,
Martin Aeschlimann,
Benjamin Stadtmüller
Abstract:
Layered 2D van der Waals materials, such as transition metal dichalcogenides, are promising for nanoscale spintronic and optoelectronic applications. Harnessing their full potential requires understanding both intrinsic transport and the dynamics of optically excited spin and charge carriers -- particularly the transition between excited spin polarization and the conduction band's intrinsic spin t…
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Layered 2D van der Waals materials, such as transition metal dichalcogenides, are promising for nanoscale spintronic and optoelectronic applications. Harnessing their full potential requires understanding both intrinsic transport and the dynamics of optically excited spin and charge carriers -- particularly the transition between excited spin polarization and the conduction band's intrinsic spin texture. Here, we investigate the spin polarization of the conduction bands of bulk WSe$_2$ using static and time-resolved spin-resolved photoemission spectroscopy, complemented by photocurrent calculations. Electron doping reveals the intrinsic spin polarization, while time-resolved measurements trace the evolution of excited spin carriers. We find that intervalley scattering is spin-conserving, with spin transport initially governed by photoexcited carriers and aligning with the intrinsic conduction band polarization after $\sim$150 fs.
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Submitted 30 May, 2025;
originally announced June 2025.
Competing signatures of intersite and interlayer spin transfer in the ultrafast magnetization dynamics
Authors:
Simon Häuser,
Sebastian T. Weber,
Christopher Seibel,
Marius Weber,
Laura Scheuer,
Martin Anstett,
Gregor Zinke,
Philipp Pirro,
Burkard Hillebrands,
Hans C. Schneider,
Bärbel Rethfeld,
Benjamin Stadtmüller,
Martin Aeschlimann
Abstract:
Optically driven intersite and interlayer spin transfer are individually known as the fastest processes for manipulating the spin order of magnetic materials on the sub 100 fs time scale. However, their competing influence on the ultrafast magnetization dynamics remains unexplored. In our work, we show that optically induced intersite spin transfer (also known as OISTR) dominates the ultrafast mag…
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Optically driven intersite and interlayer spin transfer are individually known as the fastest processes for manipulating the spin order of magnetic materials on the sub 100 fs time scale. However, their competing influence on the ultrafast magnetization dynamics remains unexplored. In our work, we show that optically induced intersite spin transfer (also known as OISTR) dominates the ultrafast magnetization dynamics of ferromagnetic alloys such as Permalloy (Ni80Fe20) only in the absence of interlayer spin transfer into a substrate. Once interlayer spin transfer is possible, the influence of OISTR is significantly reduced and interlayer spin transfer dominates the ultrafast magnetization dynamics. This provides a new approach to control the magnetization dynamics of alloys on extremely short time scales by fine-tuning the interlayer spin transfer.
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Submitted 28 April, 2023;
originally announced April 2023.