A Narrowband Spintronic Terahertz Emitter based on Magnetoelastic Heterostructures

Abstract

Narrowband terahertz (THz) radiation is crucial for high-resolution spectral identification, but a narrowband THz source driven by femtosecond (fs) laser has remained scarce. Here, it is computationally predicted that a metal/dielectric/magnetoelastic heterostructure enables converting a fs laser pulse into a multi-cycle THz pulse with a narrow linewidth down to ~1.5 GHz, which is in contrast with the single-cycle, broadband THz pulse from the existing fs-laser-excited emitters. It is shown that such narrowband THz pulse originates from the excitation and long-distance transport of THz spin waves in the magnetoelastic film, which can be enabled by a short strain pulse obtained from fs laser irradiation of the metal film when the thicknesses of the metal and magnetoelastic films both fall into a specific range. These results therefore reveal an approach to achieving optical generation of narrowband THz pulse based on heterostructure design, which also has implications in the design of THz magnonic devices.

5 figures

References in corpus (7)

• Efficient metallic spintronic emitters of ultrabroadband terahertz radiation
• Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization
• Femtosecond control of electric currents at the interfaces of metallic ferromagnetic heterostructures
• Powerful and Tunable THz Emitters Based on the Fe/Pt Magnetic Heterostructure
• Coherent elastic excitation of spin waves
• Terahertz spectroscopy for all-optical spintronic characterization of the spin-Hall-effect metals Pt, W and Cu${}_{80}$Ir${}_{20}$
• Magnon polaron formed by selectively coupled coherent magnon and phonon modes of a surface patterned ferromagnet