"A magnetorquer or magnetic torquer (also known as a torque rod) is a satellite system for attitude control, detumbling, and stabilization, consisting of a solenoid with a hard magnetic-material core. The magnetorquer creates a magnetic dipole that interfaces with an ambient magnetic field, usually Earth's, so that the counter-forces produced provide useful torque." (Polites and Gibson 1971)
Polites, Michael E, and Charles A Gibson. 1971. “A Low-Power Magnetic Torquer For Satellite Attitude Control.” In The Space Congress Proceedings. Vol. 1.