Room- and low-temperature magnetic parameters of Y$_3$AlFe$_4$O$_{12}$ garnets

TL;DR

This study investigates the magnetic properties of Y3AlFe4O12 garnet ceramics across a broad temperature range, revealing how key magnetic parameters change with temperature and providing insights for tailoring magnetic materials for technological use.

Contribution

The paper provides detailed temperature-dependent magnetic parameters of Y3AlFe4O12 garnets, including anisotropy, magnetization, and exchange stiffness, which were not previously comprehensively characterized.

Findings

Effective anisotropy constant sharply increases below 150 K.

Saturation magnetization remains relatively stable up to 250 K.

Exchange and spin wave stiffness decrease rapidly near the Curie temperature.

Abstract

Magnetic properties of Y$_3$AlFe$_4$O$_{12}$ garnet ceramics have been studied over a wide range of temperature ($3-370$ K) and magnetic fields (up to $2$ kOe). Effects of varying the temperature on some of the application-specific magnetic characteristics have been analyzed in detail. With the decrease in temperature, the effective anisotropy constant, $K_{Eff}$, is found to sharply rise below $\sim150$ K, while the saturation magnetization, $M_s$, changes only slightly ($<20\%$ within $3-250$ K). The exchange stiffness, $A_{ex}$, and spin wave stiffness, $D$, parameters mirror the relatively smooth behavior of the magnetization at low temperatures but display a rapid drop when $T$ approaches $T_C\approx436$ K. The temperature dependence of the domain wall thickness and the critical single-domain size correlate with the corresponding values for pure Y$_3$Fe$_5$O$_{12}$ (YIG) and are in agreement with the theoretical estimates. We conclude by discussing the ways of how to use the obtained results for tailoring the magnetic properties of YIG-based materials for technological applications.