Comparison of Gate Sensitivity for Spin Interference Effect between Al2O3 and SiO2 Gate Insulators on InGaAs Based Mesoscopic Ring Arrays

We demonstrated gate voltage control of spin precession in InGaAs mesoscopic ring arrays based on Rashba spin orbit interaction (SOI). We employed 100 nm ALD Al2O3 and 150 nm sputtered SiO2 gate insulators combined with large and small ring arrays to compare the gate sensitivity for the spin precession. Al’tshuler-Aronov-Spivak (AAS) oscillations were clearly observed and the oscillation phases at B = 0 switched between negative and positive by changing the gate bias voltages Vg. It corresponds to the electrical manifestation of spin rotation due to the Rashba SOI. The spin precession angle of 2π is achieved by changing Vg for 0.6 V in large ring array with Al2O3 gate whereas Vg for 5.4 V in small ring array with SiO2 gate. We can explain enhancement of the gate sensitivity in Al2O3 gate by taking the gate control of Rashba SOI parameter α and the different ring diameter into account.