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20 September 2018 Spin correlations at hopping in magnetic structures: from tunneling magnetoresistance to single-spin transistor
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Abstract
Spin correlations at hopping are responsible for large magnetoresistance at trap-assisted resonance tunneling between normal metallic and ferromagnetic electrodes. The reason for the spin correlations at hopping is the spin-selective escape rate, which results in non-zero average spin at a trap. This causes a dependence of the trap occupation and, therefore, the current on the average spin. Surprisingly, strong spin dephasing enhances the amplitude of the magnetoresistance at trapassisted tunneling from a normal metal to a ferromagnet. Spin dephasing can also boost the tunneling magnetoresistance in magnetic tunnel junctions. Spin relaxation, however, reduces the spin correlations and associated effects, as expected.

Since the spin on the trap is a vector quantity, it produces unusual correlations in multi-terminal devices. Our analysis of a three-terminal device with normal metallic and ferromagnetic electrodes and trap-assisted hopping implies that the spin correlations result in current-voltage dependences characteristic to a single-electron transistor. Importantly, the transfer characteristics are determined by the spin correlations and the spin blockade alone as, because of the finite transition rate between the trap and the normal metallic electrodes, the current is not Coulomb blocked and it always flows through the trap-source, trap-drain, and trap-gate junctions. However, when both the gate and the source electrodes are ferromagnetic with high interface spin polarizations and anti-parallel, the current through all junctions is either suppressed or it flows only between source and drain depending on the voltages applied, in complete analogy to a single electron transistor.
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Viktor Sverdlov and Siegfried Selberherr "Spin correlations at hopping in magnetic structures: from tunneling magnetoresistance to single-spin transistor", Proc. SPIE 10732, Spintronics XI, 1073235 (20 September 2018); https://doi.org/10.1117/12.2319271
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