Abstract
Spectral diffusion in the inhomogeneous paramagnetic resonance lines of and in CaW at concentration ∼ spins/cc has been studied by electron spin echo techniques. Measurements show that the spreading of excitation through the line can be approximately described by a diffusion kernel in the form of a Lorentzian function whose width is linear in time. Local field fluctuations due to spin-spin flips and spin-lattice flips appear to be the primary cause of diffusion. In (Ca,Ce)W below 4.2°K the lattice time is long, and spin-spin flips predominate, leading to a diffusion rate which is independent of temperature. In (Ca,Er)W lattice relaxation is more rapid, and the diffusion parameter varies as the lattice time. Nuclei of in the host crystal have been observed to give a modulation in the envelope of spin echoes, but the corresponding local fields are smaller than those arising from electron spins at the concentrations studied.
- Received 24 April 1961
DOI:https://doi.org/10.1103/PhysRev.123.2059
©1961 American Physical Society