Angular dependences of the switching field and coercivity for magnetic multilayer films with strain caused by lattice mismatch

The angular dependences of the switching field and coercivity for magnetic multilayer films with strain caused by lattice mismatch are studied in detail with the help of the Stoner–Wohlfarth model. The expressions or equations for determining the switching field and the coercivity are obtained analytically, taking the strain effect into consideration. With these analytical expressions, the roles of the strain and the unidirectional anisotropy (exchange coupling) are displayed clearly. Compared to the standard Stoner–Wohlfarth model (without strain), the centers of the curves of the switching field and coercivity are found to shift from π / 2 to π / 2 + θ ∗ due to the in-plane strain caused by the lattice mismatch between the film and substrate. For the ferromagnetic/antiferromagnetic exchange bias systems, the angularly dependent amplitude of the switching field or coercivity exhibits an obvious asymmetry. The staggering or separation of the peaks of the two branches of the coercivity results in a jump phenomenon in the curves for the exchange bias field and the coercivity near θ ∗ .