Enhancing Magnetization Reversal with Some Bias

In a hard drive, the bits that represent data are written with a magnetic field in close proximity to the recording surface. However, the area written and hence the information density are limited by the size of the head carrying the magnetic field, and thus other data storage methods are being explored. Chiba et al. (p. 943) report that an electrical bias can be used to enhance the magnetic properties of a ferromagnetic semiconductor, manganese-doped indium arsenide. In a field-effect device structure, the coercive field and Curie temperature of the material could be controlled by application of a gate voltage. Such manipulation even reversed the magnetization in the magnetic semiconductor, which would allow for multifunctional devices and smaller magnetic memories.