Europhys. Lett.
Volume 72, Number 2, October 2005
Page(s) 256 - 262
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 21 September 2005
Europhys. Lett., 72 (2), pp. 256-262 (2005)
DOI: 10.1209/epl/i2005-10233-9

Thermodynamic properties of Fermi systems with flat single-particle spectra

V. A. Khodel1, 2, J. W. Clark2 and M. V. Zverev1

1  Russian Research Centre Kurchatov Institute - Moscow, 123182, Russia
2  McDonnell Center for the Space Sciences and Department of Physics Washington University - St. Louis, MO 63130, USA

received 28 June 2005; accepted in final form 29 August 2005
published online 21 September 2005

The behavior of strongly correlated Fermi systems is investigated beyond the onset of a phase transition where the single-particle spectrum $\xi({\bm p})$ becomes flat. The Landau-Migdal quasiparticle picture is shown to remain applicable on the ordered side of this transition. Nevertheless, low-temperature properties evaluated within this picture show profound changes relative to results of Landau theory, as a direct consequence of the flattening of $\xi({\bm p})$. Stability conditions for this class of systems are examined, and the nature of antiferromagnetic quantum phase transitions is elucidated.

71.10.Hf - Non-Fermi-liquid ground states, electron phase diagrams and phase transitions in model systems.
71.27.+a - Strongly correlated electron systems; heavy fermions.
75.30.Cr - Saturation moments and magnetic susceptibilities.

© EDP Sciences 2005