Narrowly separatedM=0andS=0compensation points in epitaxial films of theEuzY3−zGatFe5−tO12system

Abstract

A series of 18 epitaxial films having the formula ${\mathrm{Eu}}_{z}{\mathrm{Y}}_{3\ensuremath{-}z}{\mathrm{Ga}}_{t}{\mathrm{Fe}}_{5\ensuremath{-}t}{\mathrm{O}}_{12}$ were grown by stepwise modifications of an initial yttrium iron garnet (YIG) melt, to the composition ${\mathrm{Y}}_{2}$${\mathrm{Eu}}_{1}$${\mathrm{Ga}}_{1.8}$${\mathrm{Fe}}_{3.2}$${\mathrm{O}}_{12}$. The relation between $z$ and $t$ was set to be $z=0.492t+0.172$ in order to maintain the lattice-parameter match between the ${\mathrm{Gd}}_{3}$${\mathrm{Ga}}_{5}$${\mathrm{O}}_{12}$ substrate and the films throughout the series. Relevant material parameters have been measured by microwave techniques and derived from earlier data: the effective gyromagnetic ratio ${g}_{\mathrm{eff}}$, the uniaxial anisotropy ${H}_{u}$, and Gilbert's damping parameter $\ensuremath{\alpha}$. It is clearly shown by the data that ${g}_{\mathrm{eff}}$ and $\ensuremath{\alpha}$ diverge at the angular momentum compensation point, while ${H}_{u}$ diverges at the magnetization compensation point. The separation between the angular momentum compensation point ${t}_{S}$ and the magnetization compensation point ${t}_{M}$ was found to be ${t}_{S}\ensuremath{-}{t}_{M}\ensuremath{\approx}0.06$ in accord with the theory for low $c$-site europium occupancy as compared with ${t}_{S}\ensuremath{-}{t}_{M}=0.45$ for $c$ sites entirely filled with europium.