Title:	Strong electronic correlations and magnetism in transition metals systems
DNr:	SNIC 2017/1-374
Project Type:	SNIC Medium Compute
Principal Investigator:	Igor Dimarco <igor.dimarco@physics.uu.se>
Affiliation:	Uppsala universitet
Duration:	2017-09-29 – 2018-10-01
Classification:	10304 10407
Homepage:	http://fplmto-rspt.org/
Keywords:

Abstract

Determining the electronic and magnetic structure of strongly correlated systems is a difficult task, but of crucial importance. In this project, we will investigate several strongly correlated systems, mainly by means of a combination of density functional theory and dynamical mean-field theory (DFT+DMFT). First of all, we will extend two studies that were initiated in the SNIC project 2016/1-266. We will investigate a series of Heusler compounds and their heterostructures, in particular those where a half-metallic ferromagnet (as e.g. Co2MnAl) is combined with a semiconductor (as e.g. CoMnVAl). These systems are important for various applications in spintronics, but a discrepancy still exists between theoretical predictions and experimental findings. We intend to focus on the role played by strong electronic correlations and magnetic frustration in determining the physical properties of interfaces. Another study initiated during project 2016/1-266 is the investigation of the LaMnO3|SrTiO3 superlattice. This system is predicted by theory to be half-metallic while experiments point to a ferromagnetic insulator. Our idea is to determine whether the epitaxially strained LaMnO3 surface is insulating or not, with and without an actual SrTiO3 chemical environment. We believe that the interface with SrTiO3 makes both the slab and the superlattice half-metallic due to hole doping of the Mn at the interface resulting in Mn mixed valency. Additionally, we intend to show what the influence of O vacancies and charge injections is on the electronic properties, for both thin films and in superlattices. Furthermore, we will perform several studies of the role of strong electronic correlations in semiconductors doped with magnetic impurities like (Mn,Ga)As or (Cr,Ga)As. Disorder will be included at the level of special quasi-random structures (SQS), which require large supercells and therefore a large computational effort. We will perform analyses of the inter-atomic exchange interactions and of the X-ray absorption spectra, based on the DFT+DMFT method. A different class of systems to address in this project is represented by binary transition metal carbides, nitrides and borides. These materials are good candidates for searching super-hard materials, which may be suitable for various industrial applications. We will focus on structural determination and vibrational properties, which is necessary to determine the dynamical stability. The next step will be to evaluate elastic properties and bulk moduli. This investigation will also be important to look for new 2D materials belonging to the BiXenes family, which we recently discovered. BiXenes, as most 2D materials, possess many features that make them interesting for future applications in technological devices, but their physical properties are still largely unexplored. Doping BiXenes with magnetic impurities may lead to new interesting phenomena.