Coherent spin valve phenomena and electrical spin injection in ferromagnetic/semiconductor/ferromagnetic junctions

Abstract

Coherent quantum transport in ferromagnetic/ semiconductor/ ferromagnetic junctions is studied theoretically within the Landauer framework of ballistic transport. We show that quantum coherence can have unexpected implications for spin injection and that some intuitive spintronic concepts which are founded in semi-classical physics no longer apply: A quantum spin-valve (QSV) effect occurs even in the absence of a net spin polarized current flowing through the device, unlike in the classical regime. The converse effect also arises, i.e. a zero spin-valve signal for a non-vanishing spin-current. We introduce new criteria useful for analyzing quantum and classical spin transport phenomena and the relationships between them. The effects on QSV behavior of spin-dependent electron transmission at the interfaces, interface Schottky barriers, Rashba spin-orbit coupling and temperature, are systematically investigated. While the signature of the QSV is found to be sensitive to temperature, interestingly, that of its converse is not. We argue that the QSV phenomenon can have important implications for the interpretation of spin-injection in quantum spintronic experiments with spin-valve geometries.

15 pages including 11 figures. To appear in PRB

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Cited by in corpus (11)

• Rashba effect and magnetic field in quantum wires
• Spontaneous spin-polarized current in a nonuniform Rashba interaction system
• Spin transport of electrons through quantum wires with spatially-modulated strength of the Rashba spin-orbit interaction
• Phase coherent quantum mechanical spin tranport in a weakly disordered quasi one-dimensional channel
• Beating of the oscillations in the transport coefficients of a one-dimensionally periodically modulated two-dimensional electron gas in the presence of spin-orbit interaction
• Ballistic spin field-effect transistors: Multichannel effects
• Ferromagnetic resonant tunneling diodes as spin polarimeters and polarizers
• Spin Precession and Oscillations in Mesoscopic Systems
• Multiquantum well spin oscillator
• Conductance oscillations of a spin-orbit stripe with polarized contacts
• Co-ordination between Rashba spin-orbital interaction and space charge effect and enhanced spin injection into semiconductors