Lateral spin-orbit interaction and spin polarization in quantum point contacts

Abstract

We study ballistic transport through semiconductor quantum point contact systems under different confinement geometries and applied fields. In particular, we investigate how the {\em lateral} spin-orbit coupling, introduced by asymmetric lateral confinement potentials, affects the spin polarization of the current. We find that even in the absence of external magnetic fields, a variable {\em non-zero spin polarization} can be obtained by controlling the asymmetric shape of the confinement potential. These results suggest a new approach to produce spin polarized electron sources and we study the dependence of this phenomenon on structural parameters and applied magnetic fields. This asymmetry-induced polarization provides also a plausible explanation of our recent observations of a 0.5 conductance plateau (in units of $2e^2/h$) in quantum point contacts made on InAs quantum-well structures. Although our estimates of the required spin-orbit interaction strength in these systems do not support this explanation, they likely play a role in the effects enhanced by electron-electron interactions.

Summited to PRB (2009)

References in corpus (7)

• All-Electric Quantum Point Contact Spin Valve
• Electrical generation of pure spin currents in a two-dimensional electron gas
• Possible origin of the 0.5 plateau in the ballistic conductance of quantum point contacts
• Detection of spin polarized currents in quantum point contacts via transverse electron focusing
• Kinetic magnetoelectric effect in a 2D semiconductor strip due to boundary-confinement induced spin-orbit coupling
• Opposite spin accumulations on the transverse edges by the confining potential
• Spin polarization control via magnetic barriers and spin-orbit effects

Cited by in corpus (9)

• Spin-orbit induced chirality of Andreev states in Josephson junctions
• Possible origin of the 0.5 plateau in the ballistic conductance of quantum point contacts
• All-Electrical Generation of Spin-Polarized Currents in Quantum Spin Hall Insulators
• Spin current source based on a quantum point contact with local spin-orbit interaction
• Anisotropy of the spin-orbit coupling driven by a magnetic field in InAs nanowires
• Spin filtering effect generated by the inter-subband spin-orbit coupling in the bilayer nanowire with the quantum point contact
• Magnetic Field Inducing Zeeman Splitting and Anomalous Conductance Reduction of Half-integer Quantized Plateaus in InAs Quantum Wires
• Quantized conductance in a one-dimensional ballistic oxide nanodevice
• Helical edge states induced by lateral spin-orbit coupling