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O: Fachverband Oberflächenphysik

O 49: Plasmonics and Nanooptics I: Fabrication and Application

O 49.6: Vortrag

Mittwoch, 29. März 2023, 11:45–12:00, WIL A317

Strain-driven thermal and optical instability in Ag/a-Si hyperbolic metamaterials — •Lea Forster^1,2, 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.