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<p>Ultrafast control of lattice motion in metals is a central challenge for high-frequency strain engineering and spintronic applications. Coherent strain control at terahertz (THz) frequencies in metals has remained elusive because free electrons are expected to delocalize energy beyond the optical penetration depth, preventing rapid and efficient stress generation. Here we show that robust and cost-effective metal–metal superlattices (SLs), where periodic repetitions of bilayers — each layer a few atoms thick — are deposited by sputtering, constitute thermoacoustic metamaterials that overcome this limitation. We combine femtosecond X-ray diffraction with mode-resolved density-functional theory and two-temperature modeling to show that electron pressure, rather than phonon stress, drives a large-amplitude coherent terahertz (1 THz) lattice oscillation in sputtered Pt/Cu superlattices. We establish electron pressure as an engineerable, dominant actuation mechanism in metallic metamaterials which can be tailored by the pitch and the constituent materials of the sputtered SL structure, enabling applications such as ultrafast strain-mediated antiferromagnetic spintronic devices.</p>

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Electron pressure drives THz phonons in metal–metal superlattices

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月16日

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  • Jan-Etienne Pudell,
  • Maximilian Mattern,
  • Marc Herzog,
  • Alexander von Reppert,
  • Chandan K. Singh,
  • Daniel Schick,
  • Michel Hehn,
  • Ulrike Boesenberg,
  • Angel Rodriguez-Fernandez,
  • Roman Shayduk,
  • Wonhyuk Jo,
  • Johannes Möller,
  • Jörg Hallmann,
  • James Wrigley,
  • Peter M. Oppeneer,
  • Anders Madsen,
  • Matias Bargheer

摘要

Ultrafast control of lattice motion in metals is a central challenge for high-frequency strain engineering and spintronic applications. Coherent strain control at terahertz (THz) frequencies in metals has remained elusive because free electrons are expected to delocalize energy beyond the optical penetration depth, preventing rapid and efficient stress generation. Here we show that robust and cost-effective metal–metal superlattices (SLs), where periodic repetitions of bilayers — each layer a few atoms thick — are deposited by sputtering, constitute thermoacoustic metamaterials that overcome this limitation. We combine femtosecond X-ray diffraction with mode-resolved density-functional theory and two-temperature modeling to show that electron pressure, rather than phonon stress, drives a large-amplitude coherent terahertz (1 THz) lattice oscillation in sputtered Pt/Cu superlattices. We establish electron pressure as an engineerable, dominant actuation mechanism in metallic metamaterials which can be tailored by the pitch and the constituent materials of the sputtered SL structure, enabling applications such as ultrafast strain-mediated antiferromagnetic spintronic devices.