Square Loop Properties of Copper-Manganese Ferrites

A survey of magnetic properties for the system ${\mathrm{CuFe}}_2{\mathrm{O}}_4-{\mathrm{MnFe}}_2{\mathrm{O}}_4-{\mathrm{Mn}}_3{\mathrm{O}}_4$ is reported. Saturation flux density, Curie temperature, coercivity, hysteresis loop squareness, and switching constant were determined for 60 compositions. A large compositional area having square loop properties was found. Apparently, both divalent Cu and trivalent mu contribute to squareness. Switching constant was found to decrease markedly with increasing manganese content to a low in the neighborhood of 0.6 oe-μsec. Coincident-current memory cores made from appropriate Cu-Mn ferrites have properties very similar to conventional Mg-Mn ferrites but at significantly lowered driving currents.