Future Trends in Microelectronics: Up the Nano Creek

Semiconductor Spintronics: Progress and Challenges

Emmanuel I. Rashba

Dept. of Physics, Harvard University, Cambridge, MA 02138, U.S.A.

1.   Introduction

Spin is the only internal degree of freedom of the electron, and utilizing it in the new generations of semiconductor devices is the main goal of semiconductor spintronics. Contemporary semiconductor electronics is based on electron charge only. It is expected that spin-based phenomena will provide electronic devices with new functionality, and achieving quantum computing with electron spins is among the most ambitious goals of spintronics.^1,2 During the last five years, there has been impressive progress in this field, both in experiment and in developing theoretical concepts. Since the goals are highly challenging and require overcoming a number of difficult problems, research is developing along several avenues. For example, the prospects of spin-based computing with quantum dots require an increase in the spin coherence time of gate-controlled double quantum dots by several orders of magnitude, and a great advance in this direction has been achieved recently by applying spin echo techniques.³ In what follows, we concentrate on fundamentals and on recent developments related to a different branch of spintronics: the use of spin-orbit coupling to achieve direct electrical control of electron spins in semiconductor nanostructures. Compared with magnetic control, electrical control holds promise of much higher efficiency, as ...