First-principles calculations of spin-polarized electron transport in a molecular wire: Molecular spin valve

Using first-principles density functional theory and the Landauer-Büttiker formalism, we have studied the spin-polarized transport of electrons in a benzene-1-4-dithiolate (BDT) molecule sandwiched between two Ni cluster layers, followed by nonmagnetic gold contacts. Our calculation reveals that the current for a parallel (ON) alignment of the spins at opposite ends of the molecular wire is significantly higher than for the antiparallel (OFF) alignment. We also find that the ground state of such a system has an antiparallel alignment suggesting that experiments could be performed in which an external magnetic field would be needed only for ferromagnetic alignment to switch the system from the OFF to the ON state.