ELECTRON SPIN RESONANCE OF RU3+ IN YTTRIUM GALLIUM GARNET AND YTTRIUM ALUMINUM GARNET

Electron-spin-resonance data at 4.2°K have been obtained for Ru3+ in the octahedral sites of yttrium gallium garnet (YGaG) and yttrium aluminum garnet (YAlG). The experimental values are g =3.113 0.003, g =1.148 0.002, A =63.3 0.8, and A =385 for YGaG, and g =2.88 0.02, g =1.300 0.004, A =56.4 0.7, and A =412 for YAlG, where the hyperfine constants are in units of 10-4 cm-1. From an analysis of the g values of the low-spin 4d5 system, one obtains v =-1.06 in YGaG and -0.78 in YAlG, where v is the trigonal field parameter and is the spin-orbit coupling constant. Thus the trigonal field in the garnets is negative and opposite in sign to the trigonal field of the octahedral site in corundum. The core polarization field obtained from the hyperfine constants is -220 kG/(unpaired spin) in YGaG and -250 kG/(unpaired spin) in YAlG, which is about twice the approximately constant value of -125 kG/spin found in the 3d series. © 1968 The American Physical Society.