Magnetism
A very common source of magnetic field found in nature is a dipole, with a "South pole" and a "North pole", terms dating back to the use of magnets as compasses, interacting with the Earth's magnetic field to indicate North and South on the globe. Since opposite ends of magnets are attracted, the north pole of a magnet is attracted to the south pole of another magnet. The Earth's North Magnetic Pole (currently in the Arctic Ocean, north of Canada) is physically a south pole, as it attracts the north pole of a compass.
A magnetic field contains energy, and physical systems move toward configurations with lower energy. When diamagnetic material is placed in a magnetic field, a "magnetic dipole" tends to align itself in opposed polarity to that field, thereby lowering the net field strength. When ferromagnetic material is placed within a magnetic field, the magnetic dipoles align to the applied field, thus expanding the domain walls of the magnetic domains.
Pulsed field magnet
A pulsed field magnet is a strong electromagnet which is powered by a brief pulse of electric current through its windings rather than a continuous current, producing a brief but strong pulse of magnetic field. Pulsed field magnets are used in research in fields such as materials science to study the effect of strong magnetic fields, since they can produce stronger fields than continuous magnets. The maximum field strength that continuously-powered high-field electromagnets can produce is limited by the enormous waste heat generated in the windings by the large currents required. Therefore by applying brief pulses of current, with time between the pulses to allow the heat to dissipate, stronger currents can be used and thus stronger magnetic fields can be generated. The magnetic field produced by pulsed field magnets can reach between 50 and 100 T, and lasts several tens of milliseconds.