Tesla's Magnet Mystery Shows Elon Musk Is Willing to Compromise

To magneticians, folks who study the uncanny forces some materials exert thanks to the movements of electrons and sometimes use cryptic hand gestures, the identity of Rare Earth 1 was obvious: neodymium. When added to more familiar elements, like iron and boron, the metal can help create a powerful, always-on magnetic field. But few materials have this quality. And even fewer generate a field that is strong enough to move a 4,500-pound Tesla--and lots of other things, from industrial robots to fighter jets. If Tesla planned to eliminate neodymium and other rare earths from its motors, what sort of magnets would it use instead?