Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 24: Plasmonics and Nanooptics III: Light-Matter Interaction and Spectroscopy
O 24.7: Talk
Tuesday, March 19, 2024, 12:00–12:15, MA 042
Ultra-confined THz hyperbolic phonon polaritons in HfSe2 — Ryan Kowalski1, Gonzalo Alvarez-Perez2, Niclas S. Müller3, Maximilian Obst4, Giulia Carini3, Saurabh Dixit1, Katja Diaz-Granados1, Aditha S. Senarath1, Lukas M. Eng4, Martin Wolf3, Thomas G. Folland5, Pablo Alonso-Gonzalez2, Susanne C. Kehr4, •Alexander Paarmann3, and Joshua D. Caldwell1 — 1Vanderbilt University, Nashville, TS, USA — 2University of Oviedo, Oviedo, Spain — 3Fritz Haber Institute of the Max Planck Society, Berlin, Germany — 4Institute of Applied Physics, TUD Dresden University of Technology, Dresden, Germany — 5The University of Iowa, Iowa City, IA, USA
Hyperbolic phonon polaritons have recently attracted tremendous attention due to their ability to confine infrared- to terahertz light to deeply subwavelength dimensions. So far, however, high-quality polaritons in the THz region have only been reported for very few naturally hyperbolic materials.1 Here, we experimentally demonstrate ultraconfined hyperbolic phonon polaritons in the 3-5 THz spectral range in ultrathin flakes of the van der Waals crystal HfSe2,2 with confinement factors of up to ≈80 below free space wavelength. Additonally, we also observe a unique case of strong coupling between the hyperbolic mode with the intrinsic epsilon-near-zero polariton emerging from the out-of-plane longitudinal phonon resonance within the hyperbolic band.
[1] T. de Oliveira, et, Adv. Mat. 33, 2005777 (2021).
[2] R.A. Kowalski, Adv. Opt. Mat. 10, 2200933 (2022).
Keywords: Nano-optics; Polaritons; Terahertz; Hyperbolic; Near-field optical microscopy