SKM 2023 – scientific programme
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O: Fachverband Oberflächenphysik
O 49: Plasmonics and Nanooptics I: Fabrication and Application
O 49.6: Talk
Wednesday, March 29, 2023, 11:45–12:00, WIL A317
Strain-driven thermal and optical instability in Ag/a-Si hyperbolic metamaterials — •Lea Forster1,2, Jose L. Ocana-Pujol1, Ralph Spolenak1, and Henning Galinski1 — 1Laboratory of Nanometallurgy, ETH Zurich, Switzerland — 2Laboratory for Multifunctional Ferroic Materials, ETH Zurich, Switzerland
In a hyperbolic metamaterial system of silver/amorphous-silicon multilayers we investigated the thermal instability which arises upon heating. Our analysis demonstrates that this instability is governed by the minimization of interfacial energy and anisotropic elastic strain energy caused by the mismatch of thermal expansion coefficients. Interestingly, the stacking order of the multilayer influences which of these two energy contributions dominates. We observed this behavior by a combination of FIB-SEM tomography, finite element simulations, and optical spectroscopy. Our results show that the thermal instability initiates at 300 ∘C, while the hyperbolic dispersion despite increased structural disorder persists up to 500 ∘C. These findings can lead to a better understanding of thermal instabilities in multilayers and may assist in the design of hyperbolic metamaterials for high-temperature applications.