EMERGENCE AND INFLECTION ANGLES IN THE CONFIGURATIONAL DEPENDENCE OF INTERFACE BILAYER SPIN-WAVE ENERGIES

For the two interface cubic cuts b.c.c. (110) and f.c.c. (111) we cons ider the existence regions of interface spin waves (ISWs) in a ferroma gnetic bilayer film on the two-dimensional Brillouin zone (BZ) concern ing their size and shape versus the respective interface related param eters (interface exchange coupling and intrinsic interface anisotropy) , applying the approximation of a very thick bilayer film and the meth od of Brillouin zone mapping (BZM). We emphasize the effect exerted on the BZM by varying (in the plane perpendicular to the film) the confi guration angle theta of the film magnetization with respect to the fil m normal. We predict the existence of (at most two) critical angles th eta(E) at which the ISWs emerge. The emergence angles are functions of the in-plane wave vector k(parallel to) of ISW propagation along the interface. We show that the ISW energy varies monotonously with variat ions of the angle theta attaining zero slope on the edges of the inter val of theta variability (implying simultaneously the existence of a c haracteristic point of inflection inside the interval). We prove that the nature of the monotonicity is determined unequivocally by the type of the intrinsic interface anisotropy, namely: the ISW energy grows ( decreases) monotonously with the angle theta if the interface anisotro py is of easy-plane (easy-axis) type. Moreover, we discuss the effects due to the presence of critical and inflection angles with a view to their exploitation in experimental measurements.