Transport of Spin-Polarized Electrons through an NEM-SET Structure with Ferromagnetic Electrodes

Abstract

We have investigated the spin-polarized electron transport in a magnetic nanoelectromechanical single-electron-transistor (NEM-SET), with an oscillating quantum dot (QD) coupled to two ferromagnetic electrodes. The interplay between the electronic and mechanical degrees of freedom is considered by using the quantum master equation method within Wigner phase-space. We present a concrete picture for the transition of the QD oscillations from the tunneling state to the shuttling one by analysis of the electron occupation, the effective potential and amplitude probability distribution. It is found that the development of dynamic shuttle instability is dependent on the relative orientation of two leads’ magnetizations, which arises a pronounced spin valve effect. For an asymmetric NEM-SET structure, besides the spin valve effect, we unexpectedly find that the shuttle instability is additionally dependent on the the bias-voltage polarities, exhibiting a sizable current rectification. The coexistence of two effects makes it possible to control the spin valve effect electrically or control the rectification magnetically. Subject Index: 304, 355, 375, 394