Magnetic phase diagram of ultrathin films

Abstract

By micromagnetic simulations and analytically we study the nonhomogeneous magnetization states of ultrathin films with perpendicular and in-plane anisotropy. Ground and metastable states are mapped onto a (K1,K2) phase diagram (where K1 and K2 are the first and second anisotropy constants, accordingly). It is shown that in the part of the phase diagram where K2<0, on increasing K1 or K2 the initial homogeneous in-plane magnetization distribution evolves in two sequential steps: (i) the appearance of two-phase metastable states with gradually decreasing in-plane domain fraction and (ii) a jump to a perpendicular domain state reaching 50% of the in-plane domain fraction. In the metastability area of the phase diagram, the possibility of topological frustrations in two-phase domain patterns is shown.