Demonstration of ultrafast coherent sub-picosecond magnon pulses
Abstract
Ultrafast magnonics explores routes towards energy-efficient information processing by replacing electrons with pulses of terahertz magnons. The critical, but so far elusive, requirement on the magnon pulses is the combination of high-speed and a long-range propagation while maintaining a well-defined narrow waveform of the pulses. Here, we demonstrate the launching of 0.4-picosecond magnon pulses in the altermagnetic insulator α-Fe2O3 (hematite) using broadband terahertz spin-orbit torques by an adjacent platinum layer. Phase-resolved terahertz transmission reveals that these sub-picosecond pulses travel ballistically, coherently and non-dispersively at a constant velocity of 23 nm/ps, transport angular momentum and retain their temporal waveform shape over 160 nm, with an inferred relaxation length in hundreds of nanometers or more. Beyond establishing α-Fe2O3 as an optimal platform for ultrafast magnonics, our technique introduces a high-resolution, tabletop method to directly extract dispersion relations up to high wavevectors, and explore ultrafast magnon dynamics in altermagnets and other magnetic materials with teraherz-range dynamics.
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BibTeX
@misc{kubascik2026demonstration,
title = {{Demonstration of ultrafast coherent sub-picosecond magnon pulses}},
author = {Peter Kubaščík and Miina Leiviskä and Martin Bušina and Zdenek Kašpar and Katharina Müller and Jonathan Mak and Monika Scheufele and Gal Lemut and Jose Solano and Oliver Franke and Rostislav Matuška and Jiří Jechumtál and Eva Schmorranzerová and Petr Němec and Petr Kužel and Tobias Kampfrath and Piet W. Brouwer and Matthias Opel and Stephan Geprägs and Matthias Althammer and Tomáš Jungwirth and Helena Reichlova and Lukáš Nádvorník},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.11550},
eprint = {2610.11550},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.11550},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Demonstration of ultrafast coherent sub-picosecond magnon pulses
AU - Peter Kubaščík
AU - Miina Leiviskä
AU - Martin Bušina
AU - Zdenek Kašpar
AU - Katharina Müller
AU - Jonathan Mak
AU - Monika Scheufele
AU - Gal Lemut
AU - Jose Solano
AU - Oliver Franke
AU - Rostislav Matuška
AU - Jiří Jechumtál
AU - Eva Schmorranzerová
AU - Petr Němec
AU - Petr Kužel
AU - Tobias Kampfrath
AU - Piet W. Brouwer
AU - Matthias Opel
AU - Stephan Geprägs
AU - Matthias Althammer
AU - Tomáš Jungwirth
AU - Helena Reichlova
AU - Lukáš Nádvorník
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.11550
UR - https://arxiv.org/abs/2610.11550
AB - Ultrafast magnonics explores routes towards energy-efficient information processing by replacing electrons with pulses of terahertz magnons. The critical, but so far elusive, requirement on the magnon pulses is the combination of high-speed and a long-range propagation while maintaining a well-defined narrow waveform of the pulses. Here, we demonstrate the launching of 0.4-picosecond magnon pulses in the altermagnetic insulator α-Fe_2O_3 (hematite) using broadband terahertz spin-orbit torques by an adjacent platinum layer. Phase-resolved terahertz transmission reveals that these sub-picosecond pulses travel ballistically, coherently and non-dispersively at a constant velocity of 23 nm/ps, transport angular momentum and retain their temporal waveform shape over 160 nm, with an inferred relaxation length in hundreds of nanometers or more. Beyond establishing α-Fe_2O_3 as an optimal platform for ultrafast magnonics, our technique introduces a high-resolution, tabletop method to directly extract dispersion relations up to high wavevectors, and explore ultrafast magnon dynamics in altermagnets and other magnetic materials with teraherz-range dynamics.
ER -