1. Optimum excitation wavelength and photon energy threshold for spintronic terahertz emission from Fe/Pt bilayer
- Author
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Valynn Katrine, Mag-usara, Mary Clare, Escaño, Christopher E., Petoukhoff, Garik, Torosyan, Laura, Scheuer, Julien, Madéo, Jessica, Afalla, Miezel L., Talara, Joselito E., Muldera, Hideaki, Kitahara, David R., Bacon, Makoto, Nakajima, Keshav, Dani, Evangelos Th., Papaioannou, René, Beigang, Masahiko, Tani, Valynn Katrine, Mag-usara, Mary Clare, Escaño, Christopher E., Petoukhoff, Garik, Torosyan, Laura, Scheuer, Julien, Madéo, Jessica, Afalla, Miezel L., Talara, Joselito E., Muldera, Hideaki, Kitahara, David R., Bacon, Makoto, Nakajima, Keshav, Dani, Evangelos Th., Papaioannou, René, Beigang, and Masahiko, Tani
- Abstract
Terahertz emission from ferromagnetic/non-magnetic spintronic heterostructures had been demonstrated as pump wavelength-independent. We report, however, the pump wavelength dependence of terahertz emission from an optimized Fe/Pt spintronic bilayer on MgO substrate. Maximum terahertz generation per total pump power was observed in the 1200- to 1800-nm pump wavelength range, and a marked decrease in the terahertz emission efficiency beyond 2500 nm (pump photon energies <0.5 eV) suggests a ∼0.35-eV threshold pump photon energy for effective spintronic terahertz emission. The inferred threshold is supported by previous theoretical results on the onset energy of significant spin-filtering at the Fe-Pt interface, and confirmed by Fe/Pt electronic structure calculations in this present work. The results of terahertz time-domain emission spectroscopy show the sensitivity of spintronic terahertz emission to both the optical absorptance of the heterostructure and the energy-dependent spin transport, as dictated by the properties of the metallic thin films., source:https://www.sciencedirect.com/science/article/pii/S2589004222008872
- Published
- 2022