title: Nonperturbative saddle point for the effective action of disordered and interacting electrons in 2D.
abstract: We find a nonperturbative saddle-point solution for the nonlinear sigma model proposed by Finkelstein for interacting and disordered electronic systems. Spin rotation symmetry, present in the original saddle-point solution, is spontaneously broken at one loop, as in the Coleman-Weinberg mechanism. The new solution is singular in both the disorder and triplet interaction strengths, and it also explicitly demonstrates that a nontrivial ferromagnetic state appears in a theory where the disorder average is carried out from the outset.
authors.affiliation: Department of Physics, Boston University, Boston, Massachusetts, USA.
authors.forename: C
authors.initials: C
authors.lastname: Chamon
authors.forename: E R
authors.initials: ER
authors.lastname: Mucciolo