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Shot Noise of Spin-Decohering Transport in Spin-Orbit Coupled Nanostructures

Ralitsa L. Dragomirova·Branislav K. Nikolic
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Abstract

We generalize the scattering theory of quantum shot noise to include the full spin-density matrix of electrons injected from a spin-filtering or ferromagnetic electrode into a quantum-coherent nanostructure governed by various spin-dependent interactions. This formalism yields the spin-resolved shot noise power for different experimental measurement setups--with ferromagnetic source and ferromagnetic or normal drain electrodes--whose evaluation for the diffusive multichannel quantum wires with the Rashba (SO) spin-orbit coupling shows how spin decoherence and dephasing lead to substantial enhancement of charge current fluctuations (characterized by Fano factors $> 1/3$). However, these processes and the corresponding shot noise increase are suppressed in narrow wires, so that charge transport experiments measuring the Fano factor $F_{\uparrow \to \uparrow \downarrow}$ in a ferromagnet/SO-coupled-wire/paramagnet setup also quantify the degree of phase-coherence of transported spin--we predict a one-to-one correspondence between the magnitude of the spin polarization vector and $F_{\uparrow \to \uparrow \downarrow}$.

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Ralitsa L. Dragomirova, Branislav K. Nikolic. 2006-11-17. Shot Noise of Spin-Decohering Transport in Spin-Orbit Coupled Nanostructures. https://doi.org/10.1103/physrevb.75.085328

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