Magneto-Electric Effects on Sr Z-type Hexaferrite at Room Temperature

TL;DR

This study demonstrates significant magnetoelectric effects in Sr Z-type hexaferrite at room temperature, showing potential for microwave device applications due to electric and magnetic field-induced property changes.

Contribution

It provides the first detailed measurement of magnetoelectric effects in Sr Z-type hexaferrite at room temperature, highlighting its high resistivity and potential for microwave technology.

Findings

18% change in remanence magnetization at 10,000 V/cm

16% change in dielectric constant at 1 GHz with 320 Oe magnetic field

High resistivity achieved by oxygen annealing

Abstract

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.