It has been shown that highly lossy materials, i.e. with large but finite conductivity, generate complex phase shifts of light upon reflection. As a result strong interference can take place in ultrathin films, what has been recently exploited to design absorbers, structural coloration devices and photovoltaic systems for the visible range. If applied to infrared range, this approach could deeply transform coating technology, where fabrication is ultimately limited by the minimal required layers thickness. However, highly lossy materials are scarce in the infrared, since metals, that have large losses in the visible range, act as nearly perfect conductors in the infrared.
The METACUC project aims to investigate metal composites as highly lossy materials for ultrathin infrared coatings. The research will focus on: i) metal alloys, ii) hybrid metallic island films and iii) nearly-percolated metal films. These systems can potentially provide significantly larger optical losses than pure metals due to disorder, interface damping and inter-particle coupling. The first project goal is to advance in fundamental understanding of these enhanced losses by means of several theoretical approaches (ab-initio calculations, electrodynamics simulations and modeling of percolation transition and optical properties). The theoretical work will be validated by combination of different approaches for sample fabrication and modification (thin film deposition, galvanic replacement and annealing treatments) and characterization techniques. In a second phase, the acquired knowledge will be used to devise novel infrared coatings, particularly temperature switches and ultrathin interference systems. In addition to fundamental value, the application potential of the project topic will reinforce the host institution for future industrially-oriented partnership. Finally, the project will provide opportunities to young investigators for developing a competitive research career in Croatia.