Broadly magnetic sensors and actuators rely on only a few basic principles. These include the law of induction, for magneto-inductive devices; the Ampere force law, for magnetomechanical sensors; and changes in materials properties under the action of a magnetic field, such as magnetoresistance, magneto-optics or magnetoelasticity for sensors based on magnetoelectronics (Proceedings of the 5th Conference on Magnetic Materials, Measurements and Modeling: symposium on magnetic sensors materials and devices, Ames, Iowa, USA, May 16-17, 2002). The identification and characterization of new materials with enhanced magnetic properties is important for the development of improved sensors and actuators. In some cases the identification of new materials can open up new applications for magnetic sensors and actuators which were previously not possible.