Paramagnetic Resonance ofYb3+in CaWO4

Abstract
Paramagnetic resonance of Yb3+ has been observed in single crystals of CaWO4 at 20°K and 3 cm. A tetragonal as well as two rhombic spectra were found. The tetragonal spectrum is fitted to an axial spin Hamiltonian with gII=1.058±0.002, g=3.920±0.005, |A173|=(77±1)104 cm1, |B173|=(285±1)104 cm1, |P173|<2.103 cm1, |A171|=(279±3)104 cm1, |B171|=(1034±3)104 cm1. The rhombic spectra have the y and z axes in the {110} planes. One has the z axis at 6°±1° to the crystallographic c axis and gx=3.012±0.005, gy=4.788±0.005, gz=0.975±0.003. The other has the z axis at 7°±1° to the c axis and gx=4.155±0.005, gy=3.704±0.005, gz=1.155±0.003. The spectra arise from