Today's electronic devices involve two basic properties of the electron: its charge and its spin. Historically, different classes of materials have been needed to exploit these two properties. For example, semiconductors allow control over an electrical current via the electron charge (as in transistors, diodes, etc.), while magnetic metals are used to exploit the electron spin (as in magnetic hard drives, sensors, etc.). A key objective of spin-electronics (or “spintronics”) research is to develop multi-functional, practical devices that allow precise and simultaneous control of both the charge and the spin properties of charge carriers. The development of a wide range of semiconductor alloys doped with magnetic ions – referred to as diluted magnetic semiconductors (DMSs) – represents a major step in this direction, opening up the prospect of utilizing the charge and the spin of the electron within the same material in order to create new device functionalities