Abstract
A two-dimensional electron gas (2DEG), which has recently been shown to develop in the central vertical plane of a wedge-shaped c-oriented GaN nanowall due to spontaneous polarization effect, offers a unique scenario, where the symmetry between the conduction and valence band is preserved over the entire confining potential. This results in the suppression of Rashba coupling even when the shape of the wedge is not symmetric. Here, for such a 2DEG channel, relaxation time for different spin projections is calculated as a function of donor concentration and gate bias. Our study reveals a strong dependence of the relaxation rate on the spin-orientation and density of carriers in the channel. Most interestingly, relaxation of spin oriented along the direction of confinement has been found to be completely switched off. Upon applying a suitable bias at the gate, the process can be switched on again. Exploiting this fascinating effect, an electrically driven spin-transistor has been proposed.
Highlights
When more than one eigenstates are formed below the Fermi level, DP relaxation is activated even for the x projection of spin
HSO does not commute with any of the spin components resulting in a finite relaxation time even for the spin density Sx
At an adequately high negative gate voltage, when only one subband is filled, the x-polarized spin up current injected from FMI reaches the detector electrode without losing its coherence
Summary
This assertion of zero rate of DP spin relaxation for x component of spin is strictly valid when a single subband is occupied. When more than one eigenstates are formed below the Fermi level, DP relaxation is activated even for the x projection of spin.
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