Two-magnon scattering of neutrons involving orbital transitions in antiferromagnets

Abstract

The interaction between magnons and neutrons in antiferromagnetically coupled systems is studied by taking into account the mixing of ground and excited orbital states of localized electrons of magnetic atoms due to interaction with neutrons. The magnon-neutron Hamiltonian is obtained by formulating the Heisenberg-type exchange interaction between the magnetic atoms with due cognizance of the perturbation of the electronic orbitals. The scattering cross sections are evaluated for two-magnon Raman processes with the scattering of neutrons. The role of both magnon branches is found to be important in the scattering processes. In the long-wavelength and low-temperature approximation these scattering cross sections show complicated temperature dependence, the dependence being different for different processes considered.