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

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 $\sim 150$ 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 $T_C\approx 436$ 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.

16 pages, 6 figures, full-length article submitted to a journal