Color Gradient Magnetic Film: making the invisible visible

The field structure of six magnetic objects can be seen here. Staring with a simple dipole neodymium in the center and going clockwise from the top left: fridge magnet with stripe pattern, magnetic rotor of a small motor, ring of poles of a rotor for a stepper motor, vintage ferrous classroom “dipole”, and a coded interlocking neodymium magnet. Microscopic cavities in this thin film are filled with suspended magnetic nanoparticles that interact with magnetic fields producing different colors from orange (low field strength) to dark blue (high field strength)