Parts | Days | Selection | Search | Updates | Downloads | Help

MA: Fachverband Magnetismus

MA 45: Focus: Disorder Engineering as a Tool for Material Science

MA 45.2: Invited Talk

Thursday, March 10, 2016, 15:30–16:00, H32

Electrons in disordered systems: extensions to the coherent potential approximation for short- and long-ranged order effects — •Julie Staunton¹, Alberto Marmodoro², and Arthur Ernst² — ¹University of Warwick, Coventry CV4 7AL, United Kingdom — ²Max-Planck-Institut fur Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany

The extension of the coherent potential approximation (CPA), namely the Korringa-Kohn-Rostoker (KKR)-nonlocal-CPA method, describes short- and partial long-range order effects on the electronic structure of disordered materials and has been incorporated into a full electronic density functional theory (DFT) and electronic transport formalism. Here we briefly review this method and show how it can be combined with a simple treatment of the statistical mechanics of slowly varying degrees of freedom so that, in principle, an ab-initio theory of phase transitions can be achieved along with descriptions of the development of both short- and long-range order. In this context we use the DFT-based 'disordered local moment' (DLM) picture for magnetism where slowly fluctuating local moments on atomic sites can emerge from the interacting electrons of many materials. Whilst this picture works well for many rare earth and transition metal magnets, fluctuating moments do not establish naturally over such small regions for some materials. We show how the DFT-DLM theory can be extended to these materials with the use of the KKR-NLCPA to allow for more extensive, slow magnetic fluctuations and revisit the description of the paramagnetic states of iron, cobalt and nickel.