- Introduction>
In semiconductor spintronics, electron spin rather than charge is the key property. We are studying on several spin-related devices using spin-orbit interaction. We have experimentally confirmed that the spin-orbit interaction in a semiconductor two-dimensional electron gas channel can be controlled by a gate voltage. This is the first step towards the creation of functional spin devices such as a spin field effect transistor, a spin filter, and a spin interference device.
- Gate control of spin-orbit interaction
It is well known that an external magnetic field lifts spin degeneracy. Even without an external magnetic field, an electric field perpendicular to the 2DEG yields an effective magnetic field for moving electrons. The possibility of gate control of the spin-orbit interaction was discussed in the early 1990s. However, there has been no clear experimental evidence of such controllability until we experimentally verified gate-voltage control of spin-orbit interaction in InGaAs/InAlAs heterostructures. The spin-orbit interaction parameter has since been obtained from the beating pattern in the Shubnikov-de Haas (SdH) oscillations. The dominant mechanism governing the change in the spin-orbit interaction parameter is the Rashba spin-orbit interaction. A weak anti-localization analysis has also shown that the spin-orbit interaction can be controlled by the gate voltage.
Reference
"Gate control of spin-orbit interaction in an inverted InGaAs/InAlAs heterostructure"
J. Nitta, T. Akazaki, H. Takayanagi, and T. Enoki
Phys. Rev. Lett., 78, 1335 (1997).
"Rashba spin-orbit coupling probed by the weak antilocalization analysis in InAlAs/InGaAs/InAlAs quantum wells as a function of quantum well asymmetry"
T. Koga, J. Nitta, T. Akazaki, and H. Takayanagi
Phys. Rev. Lett., 89, 046801 (2002).