Spin-based electronics promises a radical alternative to charge-based electronics, namely the possibility of logic operations with much lower power consumption than equivalent charge-based logic operations. In this paper we review three potential means of dissipationless spin transport in semiconductors with and without spin-orbit coupling: the use of spin currents, propagating modes, and orbital currents. Spin and orbital currents induced by electric fields obey a fundamentally different law than charge transport, which is dissipative. Dissipationless spin currents occur in materials with strong spin-orbit coupling, such as GaAs, while orbital currents occur in materials with weak spin-orbit coupling, such as Si, but with degenerate bands characterized by an atomic orbital index. Spin currents have recently been observed experimentally. Propagating modes are the coupled spin-charge movement that occurs in semiconductors with spin-orbit coupling. In contrast to normal charge transport, which is diffusive, the spin-charge mode can exhibit propagating transport, with low energy loss over relatively large distances (>100 μm), by funneling energy between the spin and the charge component through the spin-orbit coupling channel. This opens the possibility for spin-based transport without either spin injection or spin detection. The schemes discussed in this paper are analyzed in comparison with schemes based on molecular electronics phenomena, dilute magnetic semiconductors, etc.
All Science Journal Classification (ASJC) codes
- General Computer Science