Samarium Cobalt SmCo Magnets

Samarium Cobalt SmCo is the alternative Rare Earth magnet. It is often used in aerospace, automotive and military applications. It is usually weaker than NdFeB Neodymium at room temperature. Samarium Cobalt SmCo is capable of use in extremes of cold and heat. It also has very high coercivity making it ideal for high temperature motor applications.

Samarium Cobalt also has extremely good temperature coefficients making the magnet output very stable with small changes in temperature. It is very popular in mission-critical sensing applications.

Advantages & Disadvantages of Samarium Cobalt Magnets


  • Can be used in extremely cold conditions (e.g. to a few Kelvin above absolute zero).
  • SmCo can be used up to +300 degrees C (572F); the H rated versions up to +350 degrees C (662F).
  • High coercivity (Hci) to resist demagnetisation.
  • Above +150 to +180 degrees C (302-356F) the SmCo starts to offer more performance than NdFeB grades.
  • SmCo is regarded as being corrosion resistant.
  • Very low field strength change with varying temperature.


  • Sm2Co17 should be given a protective coating when in very damp conditions to minimise any surface corrosion risk (Sm1Co5 does not rust as it contains no iron).
  • Generally higher cost than NdFeB.
  • All magnets are brittle but SmCo is the most brittle.

Typical Applications of Samarium Cobalt SmCo

  • High-temperature Motors and Generators
  • Military applications
  • Automotive (sensors)
  • Aerospace (sensors)
  • Magnetic pump couplings
  • Oil drilling applications
  • Cryogenic applications


magnetic pump coupling was required to cope with high temperatures up to and possibly over +300 degrees C (572F). We supplied the H rated SmCo which will cope with temperatures up to +350 degrees C (662F).