Zytek's 70kW electric motor. Image: Morgan Motor Company
Automakers' first choice of magnet, the NdFeB, excels in this situation—but it also has one downside: operating temperature.
Once NdFeB magnets surpass 80 degrees Celsius (176 degrees Fahrenheit), irreversible loss of magnetization occurs.
To combat this, NdFeB magnets are often infused with heavier rare-earth metals to increase the temperatures at which they operate.
The downside to this is a loss of strength, or specifically, remanence.
The rare-earth metals, as denoted in their name, are also in short supply and raise the cost of the popular magnets.
There is one hold-out on NdFeB magnets, however: Tesla.