The rapid expansion of digital technologies is driving an increasing demand for faster and more energy-efficient computing. While electronic and optical approaches have pushed data transfer and processing speeds to new limits, they still face significant power dissipation and scalability constraints. Magnonics, which processes information using spin waves (SWs) instead of electric currents, offers a promising alternative with lower energy losses and high-speed operation.
So far, most magnonic systems rely on ferromagnets (FMs)—materials where atomic spins (tiny magnetic moments) all align in the same direction. While this allows for efficient SW generation and control, FMs operate in the GHz range, limiting their speed. In contrast, antiferromagnets (AFMs) have spins that alternate in opposite directions, cancelling their overall magnetization while enabling much higher-frequency terahertz (THz) spin waves. AFMs also switch 1,000 times faster than FMs, making them ideal for ultrafast computing. Recent breakthroughs have demonstrated THz SW generation and control in AFMs, but a key missing piece remains—THz magnetic nonlinearities. These nonlinearities, essential for SW interaction, amplification, and information processing, require fast and large-amplitude spin perturbations, which have yet to be realized.
ASTRAL aims to enter the nonlinear regime of THz magnonics by generating a new physical object—ultrashort, large-amplitude SW pulses. Similar to femtosecond laser pulses in optics, these pulses can propagate over long distances while unlocking nonlinear interactions between pulses, other SWs, and even macroscopic spin textures. AFMs provide an ideal medium for this approach, as their intrinsically high SW frequencies naturally reach the THz range and, like light waves in vacuum, follow a linear (relativistic) dispersion relation. This allows a broadband wavepacket of coherent SWs to be compressed into an ultrashort SW pulse, consisting of few-cycle, large-amplitude spin oscillations.
To achieve this, ASTRAL will leverage ultrafast laser pulses to initiate and control spin dynamics, aiming to convert femtosecond laser pulses into large-amplitude ultrashort SW pulses.
ASTRAL addresses four key objectives:
• Developing new experimental protocols for generating SW pulses with sub-1 ps durations and long propagation lengths (>1 µm).
• Designing advanced imaging techniques to visualize SW pulses in real space and track their evolution with high temporal and spatial resolution.
• Entering the nonlinear SW regime by demonstrating magnon-magnon interactions and energy redistribution mechanisms in AFMs.
• Using SW pulses to manipulate AFM domains and spin textures, paving the way for ultrafast spintronic devices.
By achieving these objectives, ASTRAL will establish the foundation for revolutionary new computing technologies, bringing THz magnonics closer to real-world applications in energy-efficient, high-speed information processing.
