Modulating Unpolarized Current in Quantum Spintronics: Visibility of Spin-Interference Effects in Multichannel Aharonov-Casher Mesoscopic Rings

Abstract

The conventional unpolarized current injected into a {\em quantum-coherent} semiconductor ring attached to two external leads can be modulated from perfect conductor to perfect insulator limit via Rashba spin-orbit (SO) coupling. This requires that ballistic propagation of electrons, whose spin precession is induced by the Aharonov-Casher phase, takes place through a single conducting channel ensuring that electronic quantum state remains a pure separable one in the course of transport. We study the fate of such spin interference effects as more than one orbital conducting channel becomes available for quantum transport. Although the conductance of multichannel rings, in general, does not go all the way to zero at any value of the SO coupling, some degree of current modulation survives. We analyze possible scenarios that can lead to reduced visibility of spin interference effects that are responsible for the zero conductance at particular values of the Rashba interaction: (i) the transmitted spin states remain fully coherent, but conditions for destructive interference are different in different channels; (ii) the transmitted spins end up in partially coherent quantum state arising from entanglement to the environment composed of orbital degrees of freedom of the same particle to which the spin is attached.

12 pages, 11 EPS color figures

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• Geometric phase in open systems
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• Spin-dependent (magneto)transport through a ring due to spin-orbit interaction
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• Non-Abelian gauge field theory of the spin-orbit interaction and a perfect spin filter
• Spin Hall Current Driven by Quantum Interferences in Mesoscopic Rashba Rings
• Anisotropic spin transport in two-terminal mesoscopic rings: the Rashba and Dresselhaus spin-orbit interactions
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• Fano resonances and electron spin transport through a two-dimensional spin-orbit-coupled quantum ring
• Quantum Rings with Rashba spin orbit coupling: a path integral approach
• Two-dimensional quantum rings with oscillating spin-orbit interaction strength: A wave function picture
• Time reversal Aharonov-Casher effect in mesoscopic rings with Rashba spin-orbital interaction
• Anomalous magnetic response of a quasi-periodic mesoscopic ring in presence of Rashba and Dresselhaus spin-orbit interactions
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• Spin and charge transport in U-shaped one-dimensional channels with spin-orbit couplings
• Non-adiabatic generation of a pure spin current in a 1D quantum ring with spin-orbit interaction
• What can we learn about the dynamics of transported spins by measuring shot noise in spin-orbit-coupled nanostructures?
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• Arbitrary qubit transformations on tuneable Rashba rings
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• Control of Josephson current by Aharonov-Casher Phase in a Rashba Ring
• Anomalous Spin-Related Quantum Phase in Mesoscopic Hole Rings
• Externally controlled selective spin transfer through a two-terminal bridge setup
• Two impurity Kondo problem under Aharonov--Bohm and Aharonov--Casher Effects
• Electron scattering from a mesoscopic disk in Rashba system
• Rashba interferometers: Spin-dependent single and two-electron interference
• Rashba Spin Interferometer
• Magnetization Transfer by a Quantum Ring Device
• Spin interference and Fano effect in electron transport through a mesoscopic ring side-coupled with a quantum dot
• Current-Conserving Aharonov-Bohm Interferometry with Arbitrary Spin Interactions
• Spin polarization via decoherence in spin-orbit active media coupled to an electron reservoir
• Formal Integration of Electron Scattering Processes via Separation of Dynamical and Geometric Contributions
• Nonadiabatic generation of spin currents in a quantum ring with Rashba and Dresselhaus spin-orbit interactions
• Time-resolved quantum spin transport through an Aharonov-Casher ring