Band splitting and relative spin alignment in bilayer systems

Abstract

It is shown that one-particle spectra of the lower Hubbard band of bilayer correlated 2D systems with different relative alignments of the spin systems in the layers differ significantly. In particular, the bilayer band splitting differs from zero for identically directed alternating spins of different layers (F z configuration), but tends to zero for antiparallel alignment (AF z configuration). It is found that the type of the alignment of the ground state changes upon an increase in the doping δ from the lower AF z configuration to the F z configuration of the alignment observed for large values of δ. The behavior of bilayer splitting in Bi2Sr2CaCu2O8+δ suggests that the configuration of the alignment may change from F z →AF z simultaneously with the superconducting transition. The effects associated with the influence of spin alignment on the magnetic excitation spectrum as a method of studying the spin structure of bilayer systems are considered for homogeneous solutions of effective spin models.