The low-temperature collapse of the Fermi surface and phase transitions in correlated Fermi systems
V. A. Khodel
National Research Centre "Kurchatov Institute", 123182 Moscow, Russia
McDonnell Center for the Space Science and Department of Physics,
Washington University, MO 63130 St.Louis, USA
Abstract
A topological crossover, associated with the collapse of the Fermi surface in strongly
correlated Fermi systems, is examined. It is demonstrated that in these systems, the temperature
domain where standard Fermi liquid results hold dramatically narrows, because the Landau regime
is replaced by a classical one. The impact of the collapse of the
Fermi surface on pairing correlations is analyzed. In the domain of the Lifshitz phase diagram
where the Fermi surface collapses, splitting of the BCS superconducting phase transition into
two different ones of the same symmetry is shown to occur.