Resonant coupling between one- and two-magnon excitations in tetramethylamine manganese trichloride (TMMC)

Abstract

Magnetic excitations of the one-dimensional zone center in tetramethylamine manganese trichloride (TMMC) were studied by neutron scattering techniques as a function of magnetic field up to 65 kOe. In addition to the previously observed anticrossing between one-magnon and two-magnon excitations, their nonlinear coupling causes a large shift in the one-magnon excitation energy at fields well in excess of the anticrossing field. The field dependence of the energy levels clearly shows that quantum corrections become progressively more important with increasing magnetic field. These results are in excellent agreement with pertubotion calculations by Osano, Shiba, and Endoh.