Spin Electronics — Is It the Technology of the Future?

The future potential of spin electronics in the areas of information storage and ultimately quantum computing has been long recognized. The many approaches current spintronics research is taking, as detailed in this report, bear testament to its future value. Two recent discoveries have rekindled interest in the utility of semiconductors as both sources and carriers of spin information. The first of these, by Awschalom and coworkers (Awschalom and Kikkawa 1999), demonstrated that optically injected spin-polarized carriers maintain their coherence over nanosecond time scales. This means that they can be transported over distances far in excess of tens of micrometers, making the transport of coherent spin information from device to device a practical reality. The second discovery, by Ohno and coworkers in Japan (Ohno et al. 1996), resulted in the fabrication of low concentration Mn substitution in GaAs epilayers with ferromagnetic ordering temperatures in excess of 100K. Other semiconducting materials with T_C higher than room temperature are in the offing. Thus the natural integration of spin-sensitive and normal semiconductor functionalities will lead to new opportunities for integrating electronics, magnetics, and photonics into single technologies with multifunctional capabilities.