Shot noise modulations in extended spin field-effect transistors.

Based on the free electron framework and Blanter-Büttiker shot noise theory, this study systematically investigated the spin-polarized shot noise characteristics in extended spin field-effect transistors. The operational behavior of these devices is governed by three interdependent parameter systems: the engineered easy-axis orientations of the ferromagnetic leads, hybrid spin-orbit coupling (SOC) effects in the semiconductor channel (incorporating both Rashba and Dresselhaus mechanisms), and three-dimensional, tunable magnetic field configurations. By employing a generalized magneto-crystalline anisotropy coordinate system, a quantum transport model was developed that could explicitly capture the interactions between non-collinear magnetization configurations and multiple SOC effects. Numerical simulations revealed that spin-resolved shot noise exhibited distinctive multi-frequency oscillatory behavior, in which amplitudes and phases could be jointly modulated by the magnetization orientation of the leads, the spatial configuration of external magnetic fields, the strength of SOC, and material composition. Notably, in resonant tunneling-assisted quantum oscillation regimes, coherent interference effects, arising from the synergistic interplay among ferromagnetic exchange interactions, tunable Zeeman subband splitting, and SOC-induced pseudomagnetic textures, enable modulation of shot noise below the Poissonian level (i.e. Fano factor <1). This study elucidated the microscopic mechanisms underlying spin-dependent transport noise in systems governed by multiple coupled fields, providing a robust theoretical basis for the development of next-generation programmable spintronic devices.