Two basic types of Rare Earth magnets

According to their materials, rare earth magnets can be classified into two basic types: Neodymium Iron Boron rare earth magnets and Samarium Cobalt rare earth magnets.
  Neodymium Iron Boron (NdFeB) - Energy products go up to 55 MGOe, can generate very high fields; however, typically needs to be used in lower temperature applications than Samarium Cobalt can withstand. Higher temperature coefficient of Br (approximately 1.1%).
  Samarium Cobalt (SmCo) - Energy products go up to 32 MGOe, can typically be used in high temperature (350°C) environments, and typically have a small thermal coefficient of Br (approximately 0.03%/degree).

Pre: Permanent Magnet Stability

Next: Measuring Permanent Magnets' Properties with Vibrating Sample Magnetometer