Title:	Strong electronic correlations and magnetism in transition metals systems
DNr:	SNIC 2016/1-266
Project Type:	SNIC Medium Compute
Principal Investigator:	Igor Dimarco <igor.dimarco@physics.uu.se>
Affiliation:	Uppsala universitet
Duration:	2016-06-01 – 2017-09-01
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 continue the studies initiated in the SNIC project 2015/1-183, which concern the role of strong correlations on the electronic and magnetic structure of transition metal (TM) elements. These studies are focused on the magneto-crystalline anisotropy of fcc Ni and on the unusual magnetic structure of bulk Cr, which are both not correctly described in standard DFT. Moreover, we are investigating how the energetic landscape for constrained magnetic moments is changed when going from DFT to DFT+DMFT. Applications include Cr, Mn, and Fe, for various crystal structures and various pressures. Another project, which is a continuation of our previous application, is the study of the surface (001) of Cr. This surface is known be ferromagnetic, but the theoretical magnetic moments are largely overestimated with respect to experimental data. Furthermore, there is a on-going debate on the nature of the narrow resonance observed experimentally just above the Fermi level. Determining if the observed feature is due to an orbital Kondo resonance or to a surface state will be the main aim of this project. In addition to these projects, we will perform studies of various Heusler compounds and their heterostructures, like Co2MnAl/CoMnVAl. We will focus on the magnetic properties and on the role of non-quasiparticle states, which are suggested to be the main responsible of the disagreement between theory and experiment about their half-metallicity. Another interesting problem to address is related to the LaMnO3|SrTiO3 superlattice, which is predicted 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. Our further purpose is to show what the influence of O vacancies and charge injections are on the electronic properties of this interesting system (both in thin films and in superlattices). Finally, we will also focus on BiXenes, which are a new family of 2D materials that we recently predicted to form from binary TM carbides. BiXenes possess many features that make them interesting for future applications in technological devices, but their physical properties are still largely unexplored. We will investigate the formation of BiXenes from a wide range of carbides and nitrides, as well as the role of the temperature in stabilizing these structures. We will also address magnetism in BiXenes, as well as in MXenes, in collaboration with experimental groups at Oak Ridge National Labs (US).