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In 1984, Bychkov and Rashba introduced a simple form of spin-orbit coupling to explain the peculiarities of electron spin resonance in two-dimensional semiconductors. Over the past 30 years, Rashba spin-orbit coupling has inspired a vast number of predictions, discoveries and innovative concepts far beyond semiconductors. The past decade has been particularly creative, with the realizations of manipulating spin orientation by moving electrons in space, controlling electron trajectories using spin as a steering wheel, and the discovery of new topological classes of materials. This progress has reinvigorated the interest of physicists and materials scientists in the development of inversion asymmetric structures, ranging from layered graphene-like materials to cold atoms. This Review discusses relevant recent and ongoing realizations of Rashba physics in condensed matter.

We have investigated the values of the Rashba spin-orbit coupling constant a in In 0.52 Al 0.48 As͞In 0.53 Ga 0.47 As͞In 0.52 Al 0.48 As quantum wells using the weak antilocalization (WAL) analysis as a function of the structural inversion asymmetry (SIA) of the quantum wells. We have found that the deduced a values have a strong correlation with the degree of SIA of the quantum wells as predicted theoretically. The good agreement between the theoretical and experimental values of a suggests that our WAL approach for deducing a values provides a useful tool in designing future spintronics devices that utilize the Rashba spin-orbit coupling. DOI: 10.1103/PhysRevLett.89.046801 PACS numbers: 72.25.Dc, 72.25.Rb, 73.20.Fz, 73.63.Hs There has been growing interest in the field of "spintronics" [1], which involves exploration of the extra degrees of freedom provided by electron spin, in addition to those due to electron charge, with a view to realizing new functionalities in future electronic devices. One key to realizing such a spin device is the utilization of the spin-orbit (SO) interaction caused by structural inversion asymmetry (SIA) (Rashba term) in quantum wells (QWs) [2], which can be artificially controlled by controlling the applied gate voltages [3 -6] and/or by the specific design of the heterostructure [7]. However, it still remains controversial whether or not the Rashba term really exists in asymmetric QWs from both the theoretical [8][9][10] and the experimental standpoints [11,12]. From the experimental point of view, the controversy arises from the difficulties in the experimental determination of the Rashba SO coupling constant a. While the existence of a spin splitting D at the Fermi energy suggests beating in the Shubnikov -de Haas (SdH) oscillations [3 -6], the D value deduced from the position of the beating node is usually different from the value of the zero-field spin splitting D 0 since D includes the effect of the Zeeman spin splitting in a finite magnetic field [13]. In addition, in order for the beating to be observed, the value of D has to be sufficiently large so that the SdH oscillation is visible at magnetic fields where the beating nodes are supposed to occur. One should also be careful about the beatinglike patterns in the SdH oscillations that are not really related to D. When the position of the Fermi energy is sufficiently close to the second lowest subband edge (within an order of k B T) and significant intersubband scattering is taking place, beatinglike patterns can be observed in the SdH oscillations [14,15]. Also a slight occupation of the second lowest subband itself may produce a beatinglike pattern as well [16]. Therefore, it is essential to develop some other independent experimental techniques for the determination of a values, that are more reliable and reproducible than the SdH beating pattern analysis, in order to clarify the fundamental issues on the Rashba SO coupling. A quantitative understanding of the Rashba mechanism is also important for realizing future ...

We propose a spin-interference device which works even without any ferromagnetic electrodes and any external magnetic field. The interference can be expected in the Aharonov-Bohm ͑AB͒ ring with a uniform spin-orbit interaction, which causes the phase difference between the spin wave functions traveling in the clockwise and anticlockwise direction. The gate electrode, which covers the whole area of the AB ring, can control the spin-orbit interaction, and therefore, the interference. A large conductance modulation effect can be expected due to the spin interference.