In the present proposal we intend to develop theoretical methods based on many-body Green's function technique to compute the interaction between electrons and spin fluctuations (magnons). The theoretical framework has recently been developed and the plan is to implement the formulation to computationally feasible scheme.
Electron-magnon interaction can have important effects on low-energy properties of magnetic materials such as the specific heat and transport properties. Very often electron-magnon interaction is studied within a model Hamiltonian such as the Heisenberg Hamiltonian. While this approach is useful in understanding the physics, it lacks the predictive capability due to the presence of adjustable parameters in the model. Our goal is to develop a truly ab initio scheme, in which the only input data is given by the atomic positions, and apply it to real materials such as the famous parent compounds of the high-temperature superconductors.. Spin-wave excitations in transition metals and their oxides are also an appropriate target for the scheme.
At a later stage we plan also to compute interaction between phonons and spin fluctuations, a very new topic that has not been much investigated neither experimentally nor theoretically. The low-energy excitations of phonons and magnons demand high computational accuracy, which in turn will require a large amount of computational resources.