The low conductance of nickel atomic junctions in the hydrogen environment is studied using the nonequilibrium Green's function theory combined with first-principles calculations. The Ni junction bridged by a H2 molecule has a conductance of approximately 0.7 G0. This conductance is contributed by the anti-bonding state of the H2 molecule, which forms a bonding state with the 3d orbitals of the nearby Ni atoms. In contrast, the Ni junction bridged by the two single H atoms has a conductance of approximately 1 G0, which is weakly spin-polarized. The spin-up channels were found to contribute mostly to the conductance at a small junction gap, while the spin-down channels play a dominant role at a larger junction gap.
@article{arxiv.1612.07517,
title = {Low conductance of the nickel atomic junctions in hydrogen atmosphere},
author = {Shuaishuai Li and Yi-Qun Xie and Yibin Hu},
journal= {arXiv preprint arXiv:1612.07517},
year = {2016}
}