Magnon Mode Transition in Real Space

Spin excitation of an ilmenite FeTiO powder sample is measured by time-of-flight inelastic neutron scattering. The dynamic magnetic pair-density function D(r, E) is obtained from the dynamic magnetic structure factor S(Q, E) by the Fourier transformation. The real space spin dynamics exhibit magnon mode transitions in the spin-spin correlation with increasing energy from no-phase-shift to π-phase-shift. The mode transition is well reproduced by a simulation using the reciprocal space magnon dispersions. This analysis provides a novel opportunity to study the local spin dynamics of various magnetic systems.