The main research directions within the proposed project concern a thorough investigation of materials with complex magnetic configurations. The emphasis is on: (i) the correct description of magnetic interactions, (ii) surface and relativistic effects, such as surface magnons in chiral magnets and (iii) lattice dynamics, including magnon-phonon coupling. The idea is to discover new materials or systems for applications in magnonics and spintronics. The mentioned studies could prove relevant for finding efficient ways of building nano-scale devices for green information and communication technologies.
Making use of the resources allocated on Triolith in the last project, we were able to work on a new approach for describing magnetic interactions in non-collinear systems. This included development of the existing codes (Elk, arXiv:1702.00599). The next step is to extend this 'beyond Heisenberg' model to include relativistic effects as well. For this, further code development is necessary. Our next studies will focus also on applying our new method of calculating the magnetic interactions to a wide range of materials and investigate their magnetisation dynamics at the atomic-scale.
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 '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 Monte Carlo and atomistic spin dynamics simulations.
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, in bulk, at surfaces, in multilayers and nanostructures. 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 excitations. By intimately knowing the characteristics of the spectra, we can tune and control the propagation or blockage of spin-waves with certain frequencies.
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, Elk and the UppASD package are already running and are being used with success on Triolith.