Eur. Phys. J. B 72, 473-478 (2009)
https://doi.org/10.1140/epjb/e2009-00390-1

γ-Mn at the border between weak and strong correlations

¹ Institute for Molecules and Materials, Radboud University of Nijmegen, 6525 ED Nijmegen, The Netherlands
² Department of Physics and Materials Science, Uppsala University, Box 530, 751 21 Uppsala, Sweden
³ Department Chemie und Biochemie, Physikalische Chemie, Ludwig-Maximilians Universität München, 81377 München, Germany
⁴ B. Verkin Institute for Low Temperature Physics and Engineering, 47 Lenin Avenue, Kharkov, Ukraine
⁵ Institute of Theoretical Physics, University of Hamburg, 20355 Hamburg, Germany

Corresponding author: ^a igor.dimarco@fysik.uu.se

Received: 3 June 2009
Revised: 6 September 2009
Published online: 20 November 2009

Abstract

We investigate the role of magnetic fluctuations in the spectral properties of paramagnetic γ-Mn. Two methods are employed. The Local Density Approximation plus Dynamical Mean-Field Theory together with the numerically exact quantum Monte-Carlo solver is used as a reference for the spectral properties. Then the same scheme is used with the computationally less demanding perturbative spin-polarized fluctuation-exchange solver in combination with the Disordered Local Moment approach, and photoemission spectra are calculated within the one-step model. It is shown that the formation of local magnetic moments in γ-Mn is very sensitive to the value of Hund's exchange parameter. Comparison with the experimental photoemission spectra demonstrates that γ-Mn is a strongly correlated system, with the Hubbard band formation, which cannot be described by the perturbative approach. However, minor change of parameters would transform it into a weakly correlated system.