Atomistic spin dynamics in complex magnets
The main research directions within the frame of the proposed project concern a thorough investigation of materials with complex magnetic configurations, with emphasis on: (i) surface and relativistic effects, such as surface magnons in chiral magnets and (ii) magnonic devices. Furthermore, we shall start a new study on magnon spintronics in March (and a new post-doc will join the group). These studies could prove relevant for finding efficient ways of building nano-scale devices for green information and communication technologies.In connection to the mentioned directions, studies that lead to a deeper understanding of magnetic interactions in complex systems (inter-metallic compounds, non-collinear magnets, complex oxides - where orbital hybridisations are strong) will be pursued. The first studies will be directed to the correct description of the magnetic interactions in non-collinear systems, together with a detailed study of their magnetisation dynamics at the atomic-scale. The aim is to elucidate the origin of complex magnetic interactions and to describe their static and dynamic behaviour. In some cases this requires us to go beyond the standard Heisenberg model for magnetic systems. For this purpose, the existing codes will be further developed. We shall perform the mentioned investigations from a theoretical point of view, aiming to corroborate our results with state-of-the-art experimental data and to motivate with our predictions further experimental studies. We shall make use of an atomistic description of the magnetisation dynamics in addition to (fully-)relativistic 'ab initio' methods. By correlating these two approaches (which are being constantly improved), we create powerful tools which give insightful information about the physics governing nano-scale magnetization dynamics. The theoretical studies will be performed in two steps. First, by means of (fully-)relativistic, spin-polarized 'ab initio' methods, the electronic structure and the magnetic properties of the systems under consideration will be investigated. In the second step, the information obtained from the first principles calculations is used as starting point for the atomistic spin dynamics simulations (within UppASD). The allocated computational time will be used for simulations and code development. The main focus is the investigation of non-collinear magnetism and spin-waves excitation spectra at surfaces and in multilayers. The magnon spectra in non-collinear magnets differ drastically from the ones corresponding to anti- and ferro-magnets. We aim at having an accurate description of the magnon spectra in complex magnetic structures and to be able to tune and control the spin-waves. By intimately knowing the characteristics of the spectra, we can tune and control the propagation or blockage of spin-waves with certain frequencies. All the codes and methods that we will use for this project (KKR, FLAPW, UppASD etc) are versatile and their performances have been tested on a wide range of systems and properties. They are well established methods in the electronic structure and spin-dynamics community. KKR-based codes and the UppASD package are already running and are being used with success on Triolith.