Tuesday, May 24, 2016

Abstract-Efficient metallic spintronic emitters of ultrabroadband terahertz radiation

  • T. Seifert,
  • S. Jaiswal,
  • U. Martens,
  • J. Hannegan,
  • L. Braun,
  • P. Maldonado,
  • F. Freimuth,
  • A. Kronenberg,
  • J. Henrizi,
  • I. Radu,
  • E. Beaurepaire,
  • Y. Mokrousov,
  • P. M. Oppeneer,
  • M. Jourdan,
  • G. Jakob,
  • D. Turchinovich,
  • L. M. Hayden,
  • M. Wolf,
  • M. Münzenberg,
  • M. Kläui

  • T. Kampfrath 
  • (some author names deleted from Labels at the bottom due to blogger word limit)

  • http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2016.91.html

    Terahertz electromagnetic radiation is extremely useful for numerous applications, including imaging and spectroscopy. It is thus highly desirable to have an efficient table-top emitter covering the 1–30 THz window that is driven by a low-cost, low-power femtosecond laser oscillator. So far, all solid-state emitters solely exploit physics related to the electron charge and deliver emission spectra with substantial gaps. Here, we take advantage of the electron spin to realize a conceptually new terahertz source that relies on three tailored fundamental spintronic and photonic phenomena in magnetic metal multilayers: ultrafast photoinduced spin currents, the inverse spin-Hall effect and a broadband Fabry–Pérot resonance. Guided by an analytical model, this spintronic route offers unique possibilities for systematic optimization. We find that a 5.8-nm-thick W/CoFeB/Pt trilayer generates ultrashort pulses fully covering the 1–30 THz range. Our novel source outperforms laser-oscillator-driven emitters such as ZnTe(110) crystals in terms of bandwidth, terahertz field amplitude, flexibility, scalability and cost.

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