Orthoferrites

Orthoferrites are a class of magnetic materials with the chemical formula RFeO3, where R is a rare-earth element or yttrium. They possess a perovskite-like crystal structure, specifically an orthorhombic distorted perovskite structure. This structure is characterized by the arrangement of RFeO3 octahedra. Orthoferrites are known for their complex magnetic properties, including canted antiferromagnetism and the presence of magnetic domain walls. The magnetic ordering in orthoferrites is primarily due to the superexchange interaction between iron (Fe) ions.

A key feature of orthoferrites is their weak ferromagnetism, which arises from the slight canting of the otherwise antiferromagnetically aligned Fe magnetic moments. This canting is a result of Dzyaloshinskii-Moriya interaction. The direction of this weak ferromagnetic moment can often be controlled by temperature or applied magnetic fields, leading to phenomena like spin-flop transitions or the rotation of the magnetic easy axis. This tunability makes them interesting for spintronic applications.

The rare-earth element R plays a significant role in the magnetic properties of orthoferrites. It can introduce its own magnetic moment and influence the magnetic ordering of the Fe sublattice. For instance, in some orthoferrites, the rare-earth moments can become ordered at low temperatures, leading to multiferroic behavior or complex magnetic phase diagrams. The study of orthoferrites is driven by their potential use in magnetic data storage, sensors, and microwave devices due to their magnetic anisotropy and domain wall dynamics.