Theory Department
Max Planck Institute of Microstructure Physics
1997    
1998    
1999    
2000    
2001    
2002    
2003    
2004    
2005    
2006    
2007    
2008    
2009    
2010    
2011    
2012    
2013    
2014    
2015    
2016    
2017    
2018    
2019    
2020    
2021    
Staunton, J. B., Marmodoro, A., Ernst, A.

Using density functional theory to describe slowly varying fluctuations at finite temperatures: Local magnetic moments in Gd and the "not so local" moments of Ni
Journal of Physics: Condensed Matter 26, (27),pp 274210/1-8 (2014)
We briefly describe the density functional theory (DFT)-based `disordered local moment' (DLM) picture for magnetism at finite temperatures. It shows how relatively slowly fluctuating local moments can emerge from the interacting electrons of many materials. Such entities have rigid magnitudes and fluctuate their orientations from atomic site to atomic site on a timescale long compared to other electronic times. We illustrate this theory with calculations of the magnetocaloric effect in Gd where we find excellent agreement with experiments. Fluctuating moments do not appear to establish naturally over such small regions for some other materials. We show how the DFT-DLM theory can be extended to these materials with the use of the Korringa-Kohn-Rostoker nonlocal coherent potential approximation (KKR-NLCPA) to allow for more extensive, slow magnetic fluctuations. We present the first application of this approach by revisiting the description of the magnetic fluctuations prevalent in the paramagnetic state of nickel. We find that local moments can emerge above Tc and that these form coherently over small clumps of atomic sites (4-8 sites).

TH-2014-26