Carlo Weingart

The aim of the present study is to quantify from first-principles calculations the mechanisms leading to the weak ferromagnetism ordering in two representative perovskites, LaFeO₃ and BiFeO₃. Both compounds show antiferrodistortive distortions (of different types), and BiFeO₃ also has a ferroelectric instability, whereas LaFeO₃ does not. To understand the links between these lattice distortions and the magnetism,
we decompose the three main magnetic interactions, i.e. exchange, Dzyaloshinski-Moriya and single ion anisotropy, and look at how these three interactions are affected by the amplitude and the combination of the different lattice distortions. This systematic analysis allows us to understand the coupling between structural distortions and spin canting, and propose some guidelines for the design of magnetoelectric weak ferromagnetisms.