SINGLE-PULSE NUCLEAR-SPIN ECHO IN MAGNETS

A detailed experimental investigation of a wide variety of ferromagnet ic materials has been undertaken in order to study the properties of t he single-pulse echo arising after the application of a solitary reson ance rf pulse to an inhomogeneously broadened nuclear spin system. The investigation is based on a comparative analysis of the sin,ale-and t wo-pulse echo. By means of a de magnetic-field pulse applied coinciden t with the exciting rf pulse, the crucial role of edge distortions of the latter in the formation of the single-pulse echo has been demonstr ated. The experimental data are compared with computer calculations pe rformed 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 equ ations for a pulse with phase shifted edges results in the formation o f a single-pulse echo. The calculated echo profiles are sensitively de pendent upon the pulse distortion parameters, and show reasonable agre ement with the corresponding experimental data.