theoretical and experimental studies of various oxide and nitride semiconductors, which apparently seemed to confirm room temperature ferromagnetism in nearly any semiconductor or insulator material heavily doped by transition metal impurities. However, early Density functional theory (DFT) studies were clouded by band gap errors and overly delocalized defect levels, and more advanced DFT studies refute most of the previous predictions of ferromagnetism. Likewise, it has been shown that for most of the oxide based materials studies for magnetic semiconductors do not exhibit an intrinsic carrier-mediated ferromagnetism as postulated by Dietl et al. To date, GaMnAs remains the only semiconductor material with robust coexistence of ferromagnetism persisting up to rather high Curie temperatures around 100–200 K. Materials The manufacturability of the materials depend on the thermal equilibrium solubility of the dopant in the base material. E.g., solubility of many dopants in zinc oxide is high enough to prepare the materials in bulk, while some other materials have so low solubility of dopants that to prepare them with high enough dopant concentration thermal nonequilibrium preparation mechanisms have to be employed, e.g. growth of thin films. Permanent magnetization has been observed in a wide range of semiconductor based materials. Some of them exhibit a clear correlation between carrier concentration and magnetization, including the work of T. Story and co-workers where they demonstrated that the ferromagnetic Curie temperature of Mn2+-doped Pb1−xSnxTe can be controlled by the carrier concentration. The theory proposed by Dietl required charge carriers in the case of holes to mediate the magnetic coupling of manganese dopants in the prototypical magnetic semiconductor, Mn2+-doped GaAs. If there is an insufficient hole concentration in the magnetic semiconductor, then the Curie temperature would be very low or would exhibit only paramagnetism. However, if the hole concentration is high (>~1020 cm−3), then the Curie temperature would be higher, between 100–200 K. However, many of the semiconductor materials studied exhibit a permanent magnetization extrinsic to the semiconductor host material. A lot of the elusive extrinsic ferromagnetism (or phantom ferromagnetism) is observed in thin films or nanostructured materials. Several examples of proposed ferromagnetic semiconductor materials are listed below. Notice that many of the observations and/or predictions below remain heavily debated. Manganese-doped indium arsenide and gallium arsenide (GaMnAs), with Curie temperature around 50–100 K and 100–200 K, respectively Manganese-doped indium antimonide, which becomes ferromagnetic even at room temperature and even with less than 1% Mn. Oxide semiconductors Manganese- and