Understanding the Spin Transport in H2O-Adsorbed CNT-Based Magnetic Tunnel Junction

We calculate the important parameters based on spin-dependent quantum transport properties in water (H 2 O)-adsorbed CNT-based magnetic tunnel junction (MTJ) with half-metallic magnet (HMM) or half-metallic ferromagnet (HMF) electrodes. Adsorption of H 2 O on CNT reduces the band gap. H 2 O-adsorbed CNT becomes less suitable as tunnel barrier. It is found that H 2 O adsorption introduces transmission states in anti-parallel configuration which are seen as spikes in its transmission spectrum. This reduces tunnel magneto-resistance (TMR) of the MTJ structure. The value of TMR obtained in this structure is ∼ 80% at 0 V bias point, and it attains a value of 96.7% at 0.3 V bias. TMR of this structure is less than that structure having a bare CNT. Spin filtration or spin polarization of ∼ 100% is attained at all bias voltages in parallel configuration (PC) whereas in the case of anti-parallel configuration (APC), spin filtration is 84.2% at 0.9 V bias which is caused by introduction of spikes in spin-down transmission spectrum of APC. This suggests that water adsorption badly affects the performance of the MTJ devices.