Ferromagnetic Hysteresis Behavior of Ferroic and Multiferroic Ceramics From 100 to 400 K for Nonlinear Pulse Forming Line Applications

Microwave generation in ferromagnetic nonlinear pulse forming lines (NPFLs) depends strongly on material properties, particularly the damped gyromagnetic precession of a ferrite’s magnetic moments. Additionally, temperature-dependent material properties, such as saturation magnetization and coercivity, are critical for assuring stable operation due to their influence on the output center frequency. In this study, we measured the temperature-dependent hysteresis behavior of both ferrous and multiferroic composites for NPFL applications. We manufactured ferrous materials [nickel zinc ferrite (NZF), yttrium iron garnet (YIG), and cobalt ferrite (CoFe)] using the standard ceramic processing methods and characterized them from 100 to 400 K using vibrating sample magnetometry. Additionally, multiferroic materials were manufactured by adding barium strontium titanate (BST) and were characterized using the same methods. Most ferroic and multiferroic samples agree with Kneller’s and Bloch’s laws, which state that the temperature-dependent coercivity and saturation magnetization vary as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T^{1/2}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${T}^{3/2}$ </tex-math></inline-formula>, respectively. Cobalt samples deviated slightly from Kneller’s law, while NZF deviated from Bloch’s law at temperatures below 200 K. For all samples, saturation magnetization decreased with increasing temperature and coercivity increased with decreasing temperature. These results provide a baseline analysis into temperature-dependent material properties for NPFL applications.