Peculiarities of Rabi oscillations and free induction decay in two-component nuclear spin systems with Ising nuclei interactions

TL;DR

This paper provides an analytical study of Rabi oscillations and free induction decay in two-component nuclear spin systems with Ising interactions, revealing nonlinear effects and multiple echoes due to phase interactions.

Contribution

It introduces an analytical model for nuclear spin dynamics considering Ising interactions in two-phase systems, highlighting nonlinear effects and echo formation.

Findings

Additional harmonics in Rabi oscillations due to nonlinearity.

Multiple echoes in free induction decay caused by Ising interactions.

Non-monotonic damping and amplitude modulation from subsystem coupling.

Abstract

Nuclear spin systems in manganites, having separation of ferromagnetic and antiferromagnetic phases, which are manifested as two lines in the NMR spectrum, are studied. Taking into account the Ising nuclear interaction, we obtain an analytical description of Rabi oscillations and free induction decay in two-component nuclear spin systems when a radio-frequency pulse non-resonantly excites the nuclei of one magnetic phase and resonantly the nuclei of the other phase. It is revealed that the nonlinearity of interaction between the nuclei of these phases results in additional harmonics in the Rabi oscillations of the non-resonantly excited subsystem. We also show that the Ising interaction inside this subsystem forms multiple echoes in the free induction decay, whereas their non-monotonic damping and amplitude modulation is caused by the spin coupling between the subsystems.