Exchange Coupling of Uniaxial Magnetic Thin Films

Abstract

The properties of two uniaxial magnetic films in intimate contact have been investigated. It is shown that when the uniaxial easy axes of the two films are orthogonal, and the magnitude of the uniaxial anisotropy the same in each film, uniaxial anisotropy in the composite film vanishes, to be replaced by a field‐dependent biaxial anisotropy. The theoretical analysis relates this biaxiality to exchange coupling between the two halves of the composite film. Experimental measurements on several films are compared with the theory and imply for A, the exchange coupling constant, an average value of 0.4×10⁻⁶ erg/cm in a 66–34 Ni‐Fe alloy film.