Magnetic Properties of Transition Metal Fluoride Perovskites

Perovskite-type transition metal fluorides display a vast variety of compositional and structural variations and, as a result, a wealth of interesting magnetic behaviours. In this Chapter we present an overview of the magnetic properties of several different classes of perovskite-type 3d transition metal fluorides. Included in this discussion are cubic perovskites, such as the KMF3 (M = Mn – Ni) series that display antiferromagnetic ordering transitions at high temperatures; distorted perovskite derivatives, such as the orbitally-ordered, Jahn-Teller active KCuF₃ system exhibiting one-dimensional magnetic character; layered perovskites, for example Ruddlesden-Popper phases including (K,Rb)₂MF₄ (M = Mn, Co, Ni) and (K,Rb,Cs)₂CuF₄ that demonstrate two-dimensional antiferro- and ferromagnetism, respectively; layered BaMF₄ (M = Mn, Fe, Co, Ni), an important family of geometric multiferroics; and hexagonal perovskites, such as the transition metal fluorides of the 6H hexagonal polytype that undergo ferrimagnetic ordering upon cooling. For each example, the magnetic response, and how it arises, are discussed in terms of the relevant perovskite structure type.