Single-pulse nuclear spin echo in magnets

Abstract

A detailed experimental investigation of a wide variety of ferromagnetic materials has been undertaken in order to study the properties of the single-pulse echo arising after the application of a solitary resonance rf pulse to an inhomogeneously broadened nuclear spin system. The investigation is based on a comparative analysis of the single- and two-pulse echo. By means of a dc magnetic-field pulse applied coincident with the exciting rf pulse, the crucial role of edge distortions of the latter in the formation of the single-pulse echo has been demonstrated. The experimental data are compared with computer calculations performed for a system of weakly interacting spins. The principal result of these calculations is that strictly rectangular pulses are unable to produce a single-pulse echo. However, the solution of the Bloch equations for a pulse with phase shifted edges results in the formation of a single-pulse echo. The calculated echo profiles are sensitively dependent upon the pulse distortion parameters, and show reasonable agreement with the corresponding experimental data.