Magnet
Many materials have unpaired electron spins, and the majority of these materials are paramagnetic. When the spins interact with each other in such a way that the spins align spontaneously, the materials are called ferromagnetic (what is often loosely termed as magnetic). Because of the way their regular crystalline atomic structure causes their spins to interact, some metals are ferromagnetic when found in their natural states, as ores. These include iron ore (magnetite or lodestone), cobalt and nickel, as well as the rare earth metals gadolinium and dysprosium (when at a very low temperature). Such naturally occurring ferromagnets were used in the first experiments with magnetism. Technology has since expanded the availability of magnetic materials to include various man-made products, all based, however, on naturally magnetic elements.
Rare-earth magnet
The development of rare-earth magnets began around 1966, when K. J. Strnat and G. Hoffer of the US Air Force Materials Laboratory discovered that an alloy of yttrium and cobalt, YCo, had by far the largest magnetic anisotropy constant of any material then known. The term "rare earth" can be misleading, as these metals are not particularly rare or precious; they are about as abundant as tin or lead. However rare earth ores are unevenly distributed, with the major source being China, which has led countries to classify rare earth metals as strategically important. Recent Chinese export restrictions on these materials have led other countries to initiate research programs to develop strong magnets that do not require them.