DYNAMICS OF A SYSTEM WITH 3-SPIN INTERACTION IN THE APPROXIMATION OF A GAUSSIAN FLUCTUATING LOCAL-FIELD

For a system of spins with effective Hamiltonian induced by a strong r f field, a study is made of the effect of fluctuations of the precessi on frequency on the form of the spin time correlation functions (TCF). In Anderson's approximation, the two-spin interaction makes a contrib ution to this frequency corresponding to a Gaussian fluctuating local field, whereas the three-spin interaction makes two contributions: one involving the square of this field and another that can be expressed in terms of a new Gaussian random variable. Expressions are obtained t hat make it possible to calculate the TCF for a Gaussian random proces s with arbitrary correlation function. Various limiting cases are disc ussed. The calculations are made for noise with correlation functions of exponential and Gaussian forms. It is shown that the properties of the TCF of a system with three-spin interaction differ from the known properties for systems with two-spin interaction.