Functional-Integral Approach to the Investigation of the Spin-Spiral Magnetic Order and Phase Separation

Abstract

We investigate a two–dimensional single-band Hubbard model with a nearest–neighbor hopping. We treat a commensurate collinear order as well as incommensurate spiral magnetic phases at a finite temperature using a Hubbard–Stratonovich transformation with a two–field representation and solve this problem in a static approximation. We argue that temperature dramatically influence the collinear and spiral magnetic phases, phase separation in the vicinity of half–filling. The results imply a possible interpretation of unusual behavior of magnetic properties of single–layer cuprates.