A neodymium magnet or NIB magnet (a variety of rare-earth magnet) is a powerful magnet made of a combination of neodymium, iron, and boron — Nd2Fe14B

Neodymium magnets are very strong relative to their mass, but are also mechanically fragile. Like other ferromagnetic materials, neodymium magnets lose their magnetism above a temperature known as the Curie point. But the most powerful grades lose their magnetism at a relatively low temperature: 80 degrees Celsius (176 degrees Fahrenheit) and above. High-temperature grades will operate at up to 200 and even 230°C but their strength is only marginally greater than that of alnico magnet.

As of 2008 magnetic component cost about $44/kg, $1.40 per BHmax.

They have replaced marginally weaker and significantly more heat-resistant samarium-cobalt magnets in most applications, due mainly to their lower cost.

Used for stabilization and angular head motors in computer hard drives, neodymium magnets are also popular with hobbyists, and a small magnet can have amazing properties — it exhibits magnetic braking when moved near a non-magnetic metal due to induced eddy currents. An excellent demonstration for students to see the effects of Lenz’s Law in non-ferrous metals may be performed by dropping a strong neodymium magnet through a copper pipe. The magnet will travel through the pipe remarkably slowly as it falls. The effect may be greatly enhanced by immersing the pipe in liquid nitrogen (thus increasing its conductivity even further) prior to dropping the magnet manufacturer.

A somewhat larger magnet interacts strongly enough with the magnetic field of the Earth to allow its tendency to align with that field to be perceived directly when holding it, essentially forming a compass. Cylinder- and disc-shaped neodymium magnets are especially responsive to the Earth’s magnetic fields. Neodymium magnets are used for the transducers in many headphones. Neodymium magnets are becoming increasingly common in loudspeakers for high-volume sound reinforcement applications. Neodymium magnets have been used several times before on the Discovery Channel television show Mythbusters in myth tests using magnetism where conventional magnets were not powerful enough. A series of 13 very large magnets of this type were proven to be able to drastically alter the trajectory path of a bullet.