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Using density functional theory and the non-equilibrium Green’s function method, we investigate the spin-dependent transport and optoelectronic properties of the graphyne-based molecular magnetic tunnel junctions (MMTJs). We find that these MMTJs exhibit an outstanding tunneling magnetoresistance (TMR) effect. The TMR value is as high as 106%. When the magnetization directions of two electrodes are antiparallel under positive or negative bias voltages, two kinds of pure spin currents can be obtained in the systems. Furthermore, under the irradiation of infrared, visible or ultraviolet light, spin-polarized photocurrents can be generated in the MMTJs, but the corresponding microscopic mechanisms are different. More importantly, if the magnetization directions of two electrodes are antiparallel, the photocurrents with different spins are spatially separated, appearing at different electrodes. This phenomenon provides a new way to simultaneously generate two spin currents. [ABSTRACT FROM AUTHOR]

The thermal properties and thermoelectric performance of one-dimensional armchair and zigzag γ-graphyne nanoribbons (γ-GYNRs) are theoretically investigated in the present study. We found that the pristine γ-GYNRs hold lower phononic thermal conductance and better figure of merit (ZT) than graphene nanorribons. The maximal ZT values for the armchair and zigzag γ-GYNRs are 0.93 and 0.61, respectively. By introducing 14C atoms, the thermoelectric conversion efficiencies of γ-GYNRs are greatly enhanced, thus the isotope effect can significantly improve the thermoelectric properties of the systems. More importantly, under a relatively low temperature, the maximal ZT of a defective zigzag γ-GYNR is as high as 2.12, indicating that γ-GYNRs are promising materials for constructing excellent thermoelectric nanodevices. [ABSTRACT FROM AUTHOR]