Spatiotemporal terahertz emission nanoscopy of spintronic photocurrent

Abstract

Capturing ultrafast spin and charge photocurrents on nanoscopic scales is essential for fundamental research in physics and engineering, as well as for future applications, such as novel spin-orbitronic devices. Accessing the fundamental dynamics driven by changes in electronic energy, linear momentum, and angular momentum requires probing at its native spatiotemporal scales: femtoseconds and nanometers. However, experimental approaches achieving this simultaneous resolution remain scarce and instrumentally demanding. Near-field probing offers promising platforms to combine ultrafast and nanometer resolution, typically with high sensitivity to out-of-plane electric fields. However, applying this technique to in-plane ultrafast coupled spin and charge currents is largely unexplored, although being highly application-relevantfrom ultrafast spin transport in 2D materials to spin-to-charge conversion in spintronic terahertz emitters (STEs). Here, we fill this gap by performing spatiotemporal terahertz (THz) emission nanoscopy (TEN) of a photoexcited fiber-coupled STE using a scanning-probe microscope. We uncover a counterintuitive, dipolar spatial evolution of the near-field THz signal, which we show originates from the out-of-plane electric fields emerging from the in-plane spin-driven charge currents. Our findings explain why TEN is sensitive to ultrafast spin-driven in-plane charge currents, paving the way for TEN to become a fully vectorial probe for the spatiotemporal mapping of coupled nanoscale THz charge and spin dynamics.

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Cite

BibTeX RIS

BibTeX

@article{paries2026spatiotemporal,
  title = {{Spatiotemporal terahertz emission nanoscopy of spintronic photocurrent}},
  author = {Felix Paries and Reza Rouzegar and Jiahua Cai and Mingcong Dai and Felix Selz and Johanna Koelbel and Geoffrey Lezier and Nicolas Tiercelin and Daniel Molter and Daniel M. Mittleman and Georg von Freymann and Xiaojun Wu and Tom S. Seifert},
  journal = {Light: Science and Applications},
  year = {2026},
  month = oct,
  doi = {10.1038/s41377-026-02468-2},
  url = {https://hal.science/hal-05835284v1},
  note = {CC BY 4.0},
}

RIS

TY  - JOUR
TI  - Spatiotemporal terahertz emission nanoscopy of spintronic photocurrent
AU  - Felix Paries
AU  - Reza Rouzegar
AU  - Jiahua Cai
AU  - Mingcong Dai
AU  - Felix Selz
AU  - Johanna Koelbel
AU  - Geoffrey Lezier
AU  - Nicolas Tiercelin
AU  - Daniel Molter
AU  - Daniel M. Mittleman
AU  - Georg von Freymann
AU  - Xiaojun Wu
AU  - Tom S. Seifert
PY  - 2026
DA  - 2026/10/08
JO  - Light: Science and Applications
DO  - 10.1038/s41377-026-02468-2
UR  - https://hal.science/hal-05835284v1
AB  - Capturing ultrafast spin and charge photocurrents on nanoscopic scales is essential for fundamental research in physics and engineering, as well as for future applications, such as novel spin-orbitronic devices. Accessing the fundamental dynamics driven by changes in electronic energy, linear momentum, and angular momentum requires probing at its native spatiotemporal scales: femtoseconds and nanometers. However, experimental approaches achieving this simultaneous resolution remain scarce and instrumentally demanding. Near-field probing offers promising platforms to combine ultrafast and nanometer resolution, typically with high sensitivity to out-of-plane electric fields. However, applying this technique to in-plane ultrafast coupled spin and charge currents is largely unexplored, although being highly application-relevantfrom ultrafast spin transport in 2D materials to spin-to-charge conversion in spintronic terahertz emitters (STEs). Here, we fill this gap by performing spatiotemporal terahertz (THz) emission nanoscopy (TEN) of a photoexcited fiber-coupled STE using a scanning-probe microscope. We uncover a counterintuitive, dipolar spatial evolution of the near-field THz signal, which we show originates from the out-of-plane electric fields emerging from the in-plane spin-driven charge currents. Our findings explain why TEN is sensitive to ultrafast spin-driven in-plane charge currents, paving the way for TEN to become a fully vectorial probe for the spatiotemporal mapping of coupled nanoscale THz charge and spin dynamics.
SN  - 2095-5545
SN  - 2047-7538
ER  -

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