Spin-current quantization in a quantum point contact with spin-orbit interaction

Abstract

We develop a realistic and analytically tractable model to describe the spin current which arises in a quantum point contact (QPC) with spin-orbit interaction (SOI) upon a small voltage is applied. In the model, the QPC is considered as a saddle point of two-dimensional potential landscape. The SOI acts within a finite region and is absent deep in the reservoirs. The SOI strength is not supposed to be strong. It is shown that the spin polarization appears in the third order of the perturbation theory as a result of definite combinations of electron transitions. They include two intersubband transitions to nearest subbands and one intrasubband transition. The spin current is proportional to the cube of the SOI strength and strongly depends on geometric parameters of the saddle point. The spin is polarized in the plane of the QPC and directed normally to the electron current if the SOI is of Rashba type. As a function of the saddle-point potential (i.e., the height of the QPC barrier), the spin conductance and especially the spin polarization have characteristic features (specifically, peaks) correlated with the charge conductance quantization steps. The peak shape depends on the length of the region where the SOI acts. In QPCs with sharp potential landscape, this picture is distorted by interference processes.

10 pages, 5 figures, to appear in Phys. Rev. B

References in corpus (13)

• Spin Accumulation in Quantum Wires with Strong Rashba Spin-Orbit Coupling
• Spontaneous spin polarization in quantum point contacts
• Spin Polarization at Semiconductor Point Contacts in Absence of Magnetic Field
• Electrical generation of pure spin currents in a two-dimensional electron gas
• Rashba spin splitting in quantum wires
• Detection of spin polarized currents in quantum point contacts via transverse electron focusing
• Enhancement of polarization in a spin-orbit coupling quantum wire with a constriction
• Polarized Electric Current in Semiclassical Transport with Spin-Orbit Interaction
• Spin Accumulation and Spin Relaxation in a Large Open Quantum Dot
• Spin-polarized electric currents in quantum transport through tubular two-dimensional electron gases
• Spin current diode based on an electron waveguide with spin-orbit interaction
• Dynamic nuclear polarisation in biased quantum wires with spin-orbit interaction
• Charge and spin transport in nanoscopic structures with spin-orbit coupling

Cited by in corpus (5)

• Signatures of spin-orbit coupling in scanning gate conductance images of electron flow from quantum point contacts
• Spin current source based on a quantum point contact with local spin-orbit interaction
• Charge and spin current in a quasi-one-dimensional quantum wire with spin-orbit coupling
• Spin-orbit coupling and resonances in the conductance of quantum wires
• Detection of spin injection into a double quantum dot: Violation of magnetic-field-inversion symmetry of nuclear polarization instabilities