Magnetism of correlated materials

Effects of electron correlations in magnetic materials, including transition and rare-earth metals, superconducting oxides, and impurities on graphene, will be discussed. Modern density functional theory (DFT) describes in principle only ground-state properties but not magnetic excitations in strongly correlated materials [1]. We use realistic dynamical mean-field theory (DFT+DMFT) which allows to investigate the correlation effects in different d- and f-electron systems. In order to investigate magnetic non-local excitations we formulate a general framework which starts from the DMFT solution for strongly correlated materials within a numerically exact continuous-time quantum Monte Carlo impurity solver [2] and use a path-integral transformation to find an optimal diagrammatic series for many-body Green functions. Prospects for self-consistent theoretical description of correlated systems with strong non-local magnetic fluctuations will be addressed.

[1] M.I. Katsnelson, V.Yu. Irkhin, L. Chioncel, A.I. Lichtenstein, and R.A. de Groot, Rev. Mod. Phys. 80, 315 (2008)
[2] E. Gull, A.J. Millis, A.I. Lichtenstein, A.N. Rubtsov, M.Troyer, and P. Werner, Rev. Mod. Phys. 83, 349 (2011)

Alexander Lichtenstein is a professor of theoretical physics at the University of Hamburg. He is well known world-wide for his contributions to the theory of magnetism, and electron-electron interactions in the solid state materials. One of his major papers on the density functional theory based calculations of the Heisenberg exchange interactions has more than 500 citations. He has a long history of an active collaboration with the scientists from the theoretical department of the Institute of Physics of the Czech Academy of Sciences, which resulted in a number of publications in high-ranking journals, and common GACR-DFG research grants. In a year 2014, the British and German Physical Societies awarded him Max Born Medal for outstanding contribution into the theory of magnetism and electron correlations in realistic materials.

The Ernst Mach Medal of the Czech Academy of Sciences will be awarded to prof. Lichtenstein on October 8th, 2015.