Nuclear Spin-Lattice Relaxation in One-Dimensional Heisenberg Ferrimagnets: Three-Magnon versus Raman Processes

TL;DR

This paper investigates nuclear spin-lattice relaxation mechanisms in one-dimensional Heisenberg ferrimagnets, highlighting the potential dominance of three-magnon processes over Raman processes through theoretical analysis and proposed experiments.

Contribution

It introduces a modified spin-wave theory to compare first- and second-order relaxation processes, emphasizing the significance of three-magnon interactions in nuclear spin relaxation.

Findings

Three-magnon relaxation process can dominate over Raman process.

Theoretical analysis suggests conditions favoring three-magnon processes.

Model experiments are proposed to verify the dominance of three-magnon relaxation.

Abstract

Nuclear spin-lattice relaxation in one-dimensional Heisenberg ferrimagnets is studied by means of a modified spin-wave theory. We consider the second-order process, where a nuclear spin flip induces virtual spin waves which are then scattered thermally via the four-magnon exchange interaction, as well as the first-order process, where a nuclear spin directly interacts with spin waves via the hyperfine interaction. We point out a possibility of the three-magnon relaxation process predominating over the Raman one and suggest model experiments.