BRILLOUIN-ZONE MAPPING OF THE EXISTENCE CONDITIONS FOR INTERFACE BILAYER SPIN-WAVES - EFFECTS OF THE CONFIGURATION OF THE FILM MAGNETIZATION

For the two interface cubic cuts: sc(110) and sc(111) we consider the existence regions of interface spin-waves of a ferromagnetic bilayer f ilm on the two-dimensional Brillouin zone as to their size and shape v ersus the respective interface related parameters (interface exchange coupling and intrinsic interface anisotropy) applying the approximatio n of a very thick bilayer film and the method of Brillouin zone mappin g (the three (100) interface cubic orientations have been dealt with e arlier [Phys. Rev. B 51, 16008 (1995)]). Of particular interest to us still remains the emergence of interface spin-waves induced by varying dynamic quantities such as the in-plane propagation wave vector k(par allel to). Moreover, in our present investigation, we put especial emp hasis on the effect exerted on the Brillouin zone mapping by varying ( in the plane perpendicular to the film) the configuration angle theta of the film magnetization with respect to the film normal. We predict the existence of (at the most two) critical angles theta(c) at which t he interface spin-waves emerge. These critical angles are functions of the in-plane wave vector k(parallel to) of interface spin-wave propag ation along the interface. Finally, we discuss the effects due to the presence of critical angles with a view to their exploitation in exper imental measurements.