<p dir="ltr">Hybrid metamaterials have garnered significant attention in recent years owing to their unique properties not found in natural materials. These materials are engineered by integrating two or more distinct materials at the nanoscale, forming various microstructures such as particle-in-matrix, pillar-in-matrix, and multilayers. The recent development of vertically aligned nanocomposites (VANs) offers a platform in forming pillar-in-matrix metamaterials in a self-assembled fashion. Transition metal nitrides, such as titanium nitride (TiN), are interesting materials for VAN designs due to their outstanding plasmonic properties, chemical stability, and compatibility with various functional materials. However, the current range of material selection and morphological demonstrations in two-phase nitride-based nanocomposites is limited. There is a growing need for a deeper understanding of the self-assembly growth mechanism and greater freedom in structural and property tunability of nitride-based VANs to develop the next generation of integrated photonic and electronic devices.</p><p dir="ltr">This dissertation investigates the design, growth mechanisms, and tunability of nitride-based VANs for advanced metamaterial applications. The first chapter focuses on integrating ferromagnetic CoFe<sub>2</sub> into a plasmonic TiN matrix to achieve anisotropic optical and magnetic properties, as well as coupling effects between the two phases. In the second chapter, a third phase, gold (Au), is introduced into TiN-CoFe<sub>2</sub> VANs in a core-shell configuration, demonstrating enhanced tunability in microstructure and resultant properties, such as distinct hyperbolic behavior and switchable magnetic easy axis. The third chapter extends the exploration into three-dimensional (3D) nanostructured films by combining different VAN films (e.g., TiN-CoFe<sub>2</sub>, TaN-CoFe<sub>2</sub>) in multilayer configurations, demonstrating highly tunable optical properties along with ferromagnetic response. This 3D nanocomposite approach highlights the potential for advanced tunability in metamaterials beyond traditional two-phase VAN designs. The fourth chapter explores the control of stoichiometry and phase composition in TiN-CuO systems. By systematically adjusting oxygen partial pressure during deposition, a gradual transition from metallic to dielectric behavior in these nanocomposite films has been observed. This investigation provides valuable insights into the comprehensive understanding of the interaction processes within hybrid nanocomposites during self-assembly. Overall, this thesis presents diverse methodologies for tuning microstructures and functionalities within nitride-based VAN systems, showing potentials for advanced applications in optics, magnetics, and beyond in metamaterial research.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/27238890 |
| Date | 16 October 2024 |
| Creators | Jiawei Song (9357755) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/_b_Multi-phase_Nitride-based_Metamaterial_Thin_Films_towards_Tunable_Microstructure_and_Coupled_Multifunctionalities_b_/27238890 |
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