Oscillatory Tunnel Magnetoresistance in a Carbon Nanotube Based Three-Terminal Magnetic Tunnel Junction

Electrostatic control of tunnel magnetoresistance (TMR) in a carbon nanotube (CNT)-based three-terminal magnetic tunnel junction (MTJ) is critical to the development of next-generation nanospintronics. Using a quantum transport approach that explicitly considers the electronic structure of the junction including the exchange-interaction effects due to spin alignments at the ferromagnetic electrodes, we have unraveled the origin behind the gate bias dependent modulation of the TMR in a single-walled CNT-based MTJ. Akin to the experimental observation, our calculation yields an oscillatory behavior in TMR with a strong variation in the amplitude and width of the magnetoresistance signal with gate bias. We attribute the gate-bias-driven nonlinear change in the strength of spin-dependent hybridization at the nanotube/contact interface as the main cause for the observed oscillatory feature in TMR.