Magnetic and structural characterization of nanosized BaCo_xZn_{2-x}Fe_{16}O_{27} hexaferrite in the vicinity of spin reorientation transition

TL;DR

This study investigates the structural and magnetic properties of doped BaCo_xZn_{2-x}Fe_{16}O_{27} hexaferrites, focusing on spin reorientation transitions relevant for magnetic applications like refrigeration.

Contribution

It provides detailed synthesis, structural characterization, and analysis of spin reorientation transitions in doped barium ferrites, highlighting the tuning of magnetic properties through composition.

Findings

Optimal synthesis temperature for single W-phase formation.

Identification of spin reorientation transition points.

Correlation between composition and magnetic behavior.

Abstract

Numerous applications of hexagonal ferrites are related to their easy axis or easy plane magnetocrystalline anisotropy configurations. Certain W-type ferrites undergo spin reorientation transitions (SRT) between different anisotropy states on magnetic field or temperature variation. The transition point can be tuned by modifying the chemical composition, which suggests a potential application of hexaferrites in room temperature magnetic refrigeration. Here we present the results of structural and magnetic characterization of BaCo_xZn_{2-x}Fe_{16}O_{27} (0.7 \leq x \leq 2) doped barium ferrites. Fine powders were prepared using a sol-gel citrate precursor method. Crystal structures and particle size distributions were examined by X-ray diffraction and transmission electron microscopy. The optimal synthesis temperature ensuring complete formation of single W-phase with limited grain growth has been determined. Spin reorientation transitions were revealed by thermomagnetic analysis and AC susceptibility measurements.