Samarium Cobalt

Permanent magnets are those magnets that stay magnetized for a long period of time. Those are sometimes being called hard magnets. A soft or impermanent magnet is one that loses its memory of previous magnetizations. Soft magnetic materials are often used in electromagnets to enhance, often in hundreds or thousands of times, the magnetic field generated by a wire that carries an electrical current. Permanent magnets occur naturally in some rocks, particularly lodestone, but are now more commonly manufactured.

The most commonly available permanent magnets nowadays are those of Neodymium Iron Boron (NdFeB), Ceramic, and Samarium Cobalt (SmCo), as well as Aluminum Nickel Cobalt (AlNiCo).