Most multiferroic materials identified to date are transition-metal oxides, which are compounds made of (usually 3d) transition metals with oxygen and often an additional main-group cation. Transition-metal oxides are a favorable class of materials for identifying multiferroics for a few reasons:
* The localised 3d electrons on the transition metal are usually magnetic if they are partially filled with electrons.
* Oxygen is at a "sweet spot" in the periodic table in that the bonds it makes with transition metals are neither too ionic (like its neighbor fluorine, F) or too covalent (like its neighbor nitrogen, N). As a result, its bonds with transition metals are rather polarizable, which is favorable for ferroelectricity.
* Transition metals and oxygen tend to be earth abundant, non-toxic, stable and environmentally benign.
Many multiferroics have the perovskite structure. This is in part historical most of the well-studied ferroelectrics are perovskites and in part because of the high chemical versatility of the structure.
Below is a list of some the most well-studied multiferroics with their ferroelectric and magnetic ordering temperatures. When a material shows more than one ferroelectric or magnetic phase transition, the most relevant for the multiferroic behavior is given.