"Microstructural Design of Multifunctional Magnetic and Hyperbolic Vertically Aligned Nanocomposites" 

Chaoran Zhang, MSE PhD Candidate 

Advisor: Professor Haiyan Wang

ABSTRACT

Yttrium iron garnet (YIG) has received considerable interest because of its low Gilbert damping coefficient, great electrical insulation, and high magneto-optical activity, and has been widely studied for microwave, spintronic, magnonic, and photonic applications. However, the performance of YIG thin films depends strongly on their composition, crystalline quality, thickness, and interfaces. This review discusses various deposition methods and quality control, followed by representative studies of YIG-Au, YIG/NiO, and YIG-BaTiO3 with different nanocomposite architecture designs. These studies demonstrate optical tuning, interfacial magnetic coupling, and strain-mediated ferromagnetic resonance tuning. Also, they reveal challenges in controlling phase separation and preserving the intrinsic properties of the YIG matrix. The remaining questions are how to fine-tune processing conditions to form vertically aligned nanocomposites (VANs) and how interfaces affect their magnetic and optical properties. Further investigation of these questions would help guide research on YIG-NiO-Ni and related VAN systems. The aim is to achieve multifunctionality while preserving the intrinsic magnetic properties of YIG.