Effects of Fermi Surface Nesting on Magnetic Instability in Magnetic Superconductors

Abstract

Possible magnetic instability in magnetic superconductors is studied by calculating the wave number dependent susceptibility χ(q) in the presence of superconductivity. Effects of Fermi surface nesting on χ(q) are examined for three models: Free electron gas model and tightly binding cosine band model of one-dimension, and Liu’s model for imperfect nesting. All model calculations reveal that stable magnetic ordering which coexists with superconductivity is antiferromagnetic one. Possibility of an incommensurate spin density wave state is discussed.