Magnetic Friction Defies a 300-Year-Old Law of Physics
Researchers at the University of Konstanz show that Amontons’ first law of friction—the friction proportional to load—fails for magnetic materials. In a non-contact setup with two magnetic layers, friction varies with the gap, being weakest at very short and very long distances but strongest at intermediate separations where competing magnetic interactions force continual reorientation, producing dissipation purely from internal magnetic rearrangements. This could impact micro- and nano-scale devices that rely on magnetism, such as magnetic bearings.