Electron-Spin-Resonance Absorption Spectrum of Platinum in Yttrium Aluminum Garnet

Abstract

An electron-spin-resonance absorption spectrum taken at 3-cm wavelength and attributed to trivalent platinum ($5{d}^{7},{t}^{6}e$) at octahedral sites in yttrium aluminum garnet has been observed at temperatures below 120\ifmmode^\circ\else\textdegree\fi{}K. The spectrum is described by $S=\frac{1}{2}$ and $\mathrm{I}=\frac{1}{2}$ (due to the 34% abundant $^{195}\mathrm{Pt}$). There are 24 magnetically inequivalent orientations of the platinum ion per unit cell arising from what is believed to be static Jahn-Teller distortions at each of the eight inequivalent octahedral sites. The $g$ and $A$ tensors are orthorhombic with principal components ${g}_{i}=1.962$, ${g}_{j}=2.361$, ${g}_{k}=2.424$ and ${A}_{l}=99 \mathrm{Oe}$, ${A}_{m}=88 \mathrm{Oe}$, and ${A}_{n}=30 \mathrm{Oe}$. The two tensors are not diagonal in the same coordinate system and their orientations with respect to the garnet cubic directions is discussed.