▎ 摘　　要

First-principles calculations of spin-dependent electronic transport properties of a magnetic tunnel junction consisting of a H2O (water)-adsorbed graphene nanosheet sandwiched between two CrO2 half-metallic ferromagnetic (HMF) electrodes is reported. H2O adsorption on graphene opens a bandgap in the graphene nanosheet which makes it more suitable for use as a tunnel barrier in magnetic tunnel junctions. It was found that H2O adsorption suppresses transmission probabilities for a spin-down channel in the case of parallel configuration (PC) and also suppresses transmission in antiparallel configuration (APC) for both spin-up and spin-down channels which result in higher tunnel magnetoresistance (TMR) at higher bias voltages in these structures. HMF electrodes were found suitable to achieve the perfect spin filtration effect and high TMR. I-V characteristics for both parallel and antiparallel magnetization states of junction are calculated. A high value of TMR similar to 100 % is obtained at all bias voltages in the range of 0 to 1.2 V. High TMR suggests its usefulness in spin valves and other spintronics-based applications.