Mössbauer spectra of CoZn-substitutedZ-type barium ferriteBa3Co2−xZnxFe24O41

Abstract

M\"ossbauer spectra of powder and aligned ${\mathrm{Ba}}_{3}{\mathrm{Co}}_{2\ensuremath{-}x}{\mathrm{Zn}}_{x}{\mathrm{Fe}}_{24}{\mathrm{O}}_{41}$ samples with $x=0--2.0$ have been obtained and analyzed at room temperature and at $T=7\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ with applied magnetic fields of 0 and $60\phantom{\rule{0.3em}{0ex}}\mathrm{kOe}$. The relationship between M\"ossbauer parameters and magnetic properties has been studied. The magnetocrystalline anisotropy of ${\mathrm{Ba}}_{3}{\mathrm{Co}}_{2\ensuremath{-}x}{\mathrm{Zn}}_{x}{\mathrm{Fe}}_{24}{\mathrm{O}}_{41}$ is modified from the $c$ plane to the $c$ axis at Zn concentration $x=1.2--1.6$, based on the dependence of the quadrupole splitting and hyperfine field on Zn substitution for powder samples, and the values of the angle factor $b$ for aligned samples. Zn ions occupy only sites with down spin, while Co ions prefer sites with up spin. As the Zn substitution increases, the increase in saturation magnetization is attributed to the occupation of Zn ions at sites with down spin, which decreases the negative magnetization, thus increasing the net magnetization.