Abstract
By the rate equation method in sequential and cotunneling regimes, we study the transport current and tunnel magnetoresistance through a single molecule magnet asymmetrically coupled to two collinear ferromagnetic electrodes. It is observed that the direction of spin-polarization current can be inversed by spin bias voltage and the adjacent magnetic field changed with left lead’s polarization. As a consequence, the tunnel magnetoresistance can reach exceptional values beyond the usual restriction of −1 to +1. Moreover, since charge current can be zero in parallel configuration and spin current stays positive, the pure spin current appears. Thus, the system may act as a spin-valve device.
Highlights
Quantum transports through the mesoscopic system have been studied for decades.1–6 Experimentally, the scanning tunnel microscope (STM) is one of the best ways to measure transport properties, such as current, shot noise, tunnel magnetoresistance (TMR), spin accumulation, and polarization.7,8 The single molecule magnet (SMM) is considered as a typical nanoscale magnetic-tunneljunction (MTJ) since it possesses magnetic anisotropy and spin exchange interaction (SEI) between the transport electron and SMM
An individual SMM trapped in a field effect transistor geometry allows the measurement of electronic transport with great tunability
The TMR value is restricted in the region ∣TMR∣ ⩽ 1 since IP and IAP always have the same sign
Summary
Quantum transports through the mesoscopic system have been studied for decades. Experimentally, the scanning tunnel microscope (STM) is one of the best ways to measure transport properties, such as current, shot noise, tunnel magnetoresistance (TMR), spin accumulation, and polarization. The single molecule magnet (SMM) is considered as a typical nanoscale magnetic-tunneljunction (MTJ) since it possesses magnetic anisotropy and spin exchange interaction (SEI) between the transport electron and SMM. The scanning tunnel microscope (STM) is one of the best ways to measure transport properties, such as current, shot noise, tunnel magnetoresistance (TMR), spin accumulation, and polarization.. A procedure to manipulate the magnetization of the SMM has been reported in terms of the spin-polarized current injected from ferromagnetic (FM) electrodes.. IP + IAP where IP and IAP, respectively, denote the charge currents in P and AP configurations Based on this definition, the TMR value is restricted in the region ∣TMR∣ ⩽ 1 since IP and IAP always have the same sign (direction). Spin polarization of current can change sharply from +∞ to −∞ along with the spin bias increasing in the parallel configuration
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