Tunable shear strain from resonantly driven optical phonons

Magnonics is a research field complementary to spintronics, in which the quanta of spin waves (magnons) replace electrons as information carriers, promising less energy dissipation 1-3 . The development of ultrafast nanoscale magnonic logic circuits calls for new tools and materials to generate coherent spin waves with frequencies as high, and wavelengths as short, as possible 4,5 . Antiferromagnets can host spin waves at THz frequencies and are therefore seen as a future platform for the fastest and the least dissipative transfer of information 6-11 . However, the generation of short-wavelength coherent propagating magnons in antiferromagnets has so far remained elusive. Here we report the efficient emission and detection of a nanometer-scale wavepacket of coherent propagating magnons in antiferromagnetic DyFeO3 using ultrashort pulses of light. The subwavelength confinement of the laser field due to large absorption creates a strongly nonuniform spin excitation profile, enabling the propagation of a broadband continuum of coherent THz spin waves. The wavepacket features magnons with detected wavelengths down to 125 nm that propagate with supersonic velocities of more than 13 km/s into the material. The long-sought source of coherent shortwavelength spin carriers demonstrated here opens up new prospects for THz antiferromagnetic magnonics and coherence-mediated logic devices at THz frequencies.Antiferromagnetic insulators (AFMs) are prime candidates to replace ferromagnets (FMs) as active media in the quest towards high-speed spin transport and large spectral bandwidth operation [6][7][8] . Integration of AFMs in future wave-based technologies 3 crucially requires the realization of coherent (ballistic) transport of antiferromagnetic spin waves over large distances 5 . In this regard, non-uniform spin-wave modes with short wavelengths (λ ≲ 100 nm) are of particular importance: they can operate at THz clock rates, exhibit high propagation velocities and enable the miniaturization of devices down to the nanoscale. Phase-coherent ballistic spin transport in AFMs

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“…S5b). This results in oscillations in the probe pulse polarization rotation with a frequency fa given by 38,39 :…”

Section: S4 Excitation Of a Propagating Wavepacket Of Coherent Acoust...mentioning

confidence: 99%