Spin inverter and polarizer curved nanowire driven by Rashba and Dresselhaus spin–orbit interactions

• A nanowire structure acts as a spin inverter/polarizer sans an applied magnetic field.
• Periodic Rashba and uniform Dresselhaus spin–orbit couplings (SOCs) are present.
• A moderate Dresselhaus SOC is essential to obtain a nonzero output polarization P.
• Desired output P is achieved by tuning the electron energy and Rashba strength.
• The device acts as an attenuator where transmission goes to zero at given energies.

We propose in theory a curved nanowire structure that can both serve as a spin inverter and a spin polarizer driven by a periodic Rashba spin–orbit coupling (SOC) and a uniform Dresselhaus SOC. The curved section of the U-shaped quasi-one dimensional nanowire with an arc of radius R   and circumferential length πRπR is divided into segments of equal length initially having only its inherent homogeneous Dresselhaus SOC. Then a Rashba-type SOC is applied at every alternating segment. By tuning the Rashba SOC strength and the incident electron energy, this device can flip the spin at the output of an incoming spin-polarized electron. On the other hand, this same device acts as a spin filter for an unpolarized input for which an outgoing electron with a non-zero polarization can be achieved without the application of an external magnetic field. Moreover, the potential modulation caused by the periodic Rashba SOC enables this device to function as an attenuator for a certain range of incident electron energies that can make the probability current density drop to 10−4 of its otherwise magnitude in other regimes.