Ferrimagnetic Resonance in Rare-Earth Doped Yttrium Iron Garnet. I. Field for Resonance

Resonance experiments have been performed on YIG crystals doped with each of the rare earth ions except Lu, Gd, and Pm. Except for Ce these are thought to replace Y as trivalent ions. This paper presents measurements of the field for resonance in the (110) plane at 1.5°K for each of these samples. In several cases there are also data up to about 25°K. Except for Ce, Eu, and Tm the curve $H_{\mathrm{res}}$ in (110) at 1.5°K shows characteristic structure. For Pr, Ho, and Tb this structure is dominated by very narrow peaks in $H_{\mathrm{res}}$. For Nd, Sm, Dy, and Er it is relatively broad in angle. For Yb most of the structure is relatively broad in angle, but there is a very sharp but small spike in $H_{\mathrm{res}}$. Only in the case of Tb and Yb do sharp spikes appear at other than symmetry directions. In some cases the height of the peaks falls off rapidly with increasing temperature starting at the lowest temperatures, but in other cases it does not change at first, then falls off.