Magnetic / dielectric anomalies and magnetodielectric / magnetoelectric effects in Z- and W-type hexaferrites

TL;DR

This study investigates the magnetic, dielectric, and coupled magnetoelectric effects in two types of hexaferrites, revealing that magnetic and dielectric anomalies are linked to anisotropy transitions but do not necessarily indicate coupling.

Contribution

It provides a comparative analysis of Z- and W-type hexaferrites, highlighting the role of T-block structures in dielectric and magnetic responses, and clarifies the conditions for magnetodielectric and magnetoelectric effects.

Findings

Magnetic and dielectric anomalies are induced by magnetocrystalline anisotropy transition.

Dielectric response in Sr3Co2Z includes ferroelectric and magnetic contributions due to T-block structure.

Anomalies are characteristic but not sufficient indicators of MD and ME coupling.

Abstract

Two kinds of specimens, with the major phase of Sr3Co2Fe24O41 (Sr3Co2Z) and SrCo2Fe16O27 (SrCo2W) hexaferrites respectively, were fabricated through solid-state reaction. The phase composition, magnetic and dielectric properties, magnetodielectric (MD) effect, magnetoelectric (ME) effect and pyroelectric properties were studied. Results show that magnetic and dielectric anomalies are induced by the magnetocrystalline anisotropy (MCA) transition. They can be considered as characteristic properties (e.g., Sr3Co2Z at 370 K) but are not a sufficient condition for the MD and ME coupling. The T-block structure, existing in Sr3Co2Z but absent in SrCo2W, results in the dielectric response with ferroelectric (FE) and magnetic contributions.