This dissertation demonstrates that, in Co-Fe alloy systems, composition has a huge effect on both magnetic and thermal transport; and it presents research exploring the interplay between spin, charge, and lattice degrees of freedom and how they influence thermal transport and magnetic properties in ferromagnetic alloys.
This dissertation reports on the use of Time-Domain Thermo-Reflectance (TDTR) to generate two-dimensional thermal conductivity maps of two distinct material systems: ferromagnetic Co-Fe alloys; and AI-PVDF nanocomposites. The dissertation also summarizes the experimental results and discusses the use of Time-Resolved Magneto-Optic Kerr Effect (TR-MOKE) to investigate magnetization dynamics in Co-FE alloys. Through discussion of the TR-MOKE experiments, it is shown that Co-Fe compositions that exhibit low Gilbert damping parameters also feature prolonged ultrafast demagnetization upon photoexcitation, and a strong correlation exists between the dynamics at both timescales which indicates that the same physical mechanisms probably govern both phenomena. Two main results are reported from the interrogation of the thermal conductivity in Co-Fe allows: the thermal conductivity does not appear to be strongly influenced by crystalline disorder in Co-Fe alloys; and Co-Fe compositions that feature ultralow magnetic damping also exhibit significantly high non-electronic contribution to thermal transport. The dissertation is organized into the following chapters: chapter one provides an introduction to the subject matter and an overview of the research methodology; chapter two describes the macroscopic structure-function relationships in a woody protective seed casing in an Australian pyrophytic plant species; chapter three summarizes the femto-magnetism and nanosecond processional dynamics in Co-Fe alloys; chapter four presents the thermal conductivity and electrical resistivity measurements in Co-Fe alloys; chapter five provides most of the TDTR measurements and high-resolution thermal conductivity maps in AI-PVDF nanocomposite films; and chapter six summarizes the research findings and presents conclusions.