  In this paper, magnetoelectric effects of Sr Z-type hexaferrite,
Sr3Fe24Co2O41, at room temperature is measured. The change in remanence
magnetization was measured by applying a DC voltage or electric field across a
slab of hexaferrite. Changes of ~ 18% in remanence was observed in an electric
field of 10,000V/cm implying a similar change in the microwave permeability at
frequencies below 3GHz. Also, a change in dielectric constant at 1 GHz of ~16%
in a magnetic field of only 320 Oe was measured. In these types of measurements
high resistivity is critical in order to reduce current flow in the
hexaferrite. The resistivity of the hexaferrite was raised to 4.28x10^8 ohm-cm
by annealing under oxygen pressure. The measurements indicate that indeed
electric polarization and magnetization changes were induced by the application
of magnetic and electric fields, respectively. The implications for microwave
applications appear to be very promising at room temperature.
