T. Seifert, S. Jaiswal, M. Sajadi, G. Jakob, S. Winnerl, M. Wolf, M. Kläui, and T.Kampfrath:
Appl. Phys. Lett. 110 (25), 252402 (2017), pp.5;
arXiv:1703.09970 [cond-mat.mtrl-sci] (2017), pp. 7;
DOI: arXiv:1703.09970 [cond-mat.mtrl-sci]
We explore the capabilities of metallic spintronic thin-film stacks as a source of intense and broadband terahertz electromagnetic fields. For this purpose, we excite a W/CoFeB/Pt trilayer (thickness of 5.6 nm) on a large-area glass substrate (diameter of 7.5 cm) by a femtosecond laser pulse (energy 5.5 mJ, duration 40 fs, and wavelength 800 nm). After focusing, the emitted terahertz pulse is measured to have a duration of 230 fs, a peak field of 300 kV cm1, and an energy of 5 nJ. In particular, the waveform exhibits a gapless spectrum extending from 1 to 10 THz at 10% of its amplitude maximum, thereby facilitating nonlinear control over matter in this difficult-to-reach frequency range on the sub-picosecond time scale.
The original publication is available by link DOI: 10.1063/1.4986755