Microwave ferromagnetic resonance of cobalt and nickel substituted U-type hexaferrites

This paper presents accurate broad-band data on the complex relative permittivity (ε=ε\´-jε") and complex relative permeability (μ=μ\´-jμ\´\´) of two U-type hexaferrites. These hexaferrites have a general molecular formula of Ba₄Me₂Fe₃₆O₆₀ where Me is a bivalent transition-metal. In this work, Me=Co, Ni. In this paper, the dielectric and magnetic properties of these two U-type hexaferrites, Co₂U and Ni₂U, are investigated because of the potential applications of such ferrite materials in microwave devices. The dielectric and magnetic properties are obtained via the transmission-reflection technique. For Co₂U, the complex relative ε and μ are obtained from 12.4 GHz-18.0 GHz and for Ni₂U, the complex relative ε and μ are obtained from 18.0 GHz-40.0 GHz.