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Communication Dans Un Congrès Année : 2023

[Invited] Strategies for Polarization Control in Engineered Spintronic THz Emitters

Résumé

THz science took off in the 1980 with the discovery by Auston at Bell Labs of the photoconductive switch. Since then, THz science has only slowly developed, and few applications exist despite the enormous potential of the frequency band. One major challenge is the 5-12 THz frequency band, for which no good source existed until the advent of the Spintronic Inverse Spin Hall Effect terahertz emitters (ISHE STE) [1]. The physics of the ISHE inherently implies the emitted THz pulse to be strictly perpendicular to the magnetization of the spin pumping layer. This is a particularly interesting feature enabling, a compact and efficient source for time-domain terahertz ellipsometry. We will here present several polarization control strategies based on the use of STE with anisotropic and/or magnetoelastic ferromagnetic layers such as Pt(2nm)/ FeCo(0.5nm)/ TbCo2(0.8nm)/ FeCo(0.5nm) / W(2nm) or Pt(2nm) / FeCoB(1.8nm) / W(2nm) , deposited by RF sputtering. Owing to the in-plane magnetic anisotropy, we first demonstrate the polarization control of the THz emitted wave thanks to the Stoner-Wohlfarth coherent rotation of magnetization when submitted to a magnetic field along hard axis. In a second configuration, the anisotropy enables a magnetic phase transition of the Spin Reorientation Transition type. Due to the instability of the magnetization at the transition, a much higher susceptibility allows for a faster switching at much lower power. Finally, an emitter with a magnetoelastic trilayer was deposited onto a PMN-PT substrate. Thanks to the strain mediated magneto-electric effect, we experimentally demonstrated a reversible 70° THz polarization rotation by sweeping the substrate voltage over 400 V. This demonstration allows for a fully THz polarization controlled ISHE spintronic terahertz emitters not needing any control of the magnetic bias. [1] Seifert, T. et al., Nature Photonics, 10(7), 483–488.
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Dates et versions

hal-04545543 , version 1 (14-04-2024)

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  • HAL Id : hal-04545543 , version 1

Citer

Nicolas Tiercelin, Geoffrey Lezier, Pierre Kolejak, Jean-Francois Lampin, Kamil Postava, et al.. [Invited] Strategies for Polarization Control in Engineered Spintronic THz Emitters. ICMAT 2023 | 11th International Conference on Materials for Advanced Technologies, Jun 2023, Singapour, Singapore. ⟨hal-04545543⟩
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