Microscopic description of magnon-optical-phonon interaction in FeCl22H2O

A simple physical mechanism is described for the magnon-optical-phonon interaction observed in FeCl22H2O: A vibration of the waters of hydration gives rise to a modulating Coulomb potential at the Fe2+ site; this potential acts on the orbital part of the Fe2+ wave function and is coupled to the spin via the spin-orbit coupling. The calculated magnitude (1.2 cm-1) of the interaction is in remarkably good agreement with the experimental value of 1.3 cm-1. © 1972 The American Physical Society.