In resemblance of the mechanically-controlled break junction, we considered the molecule 1,4-benzenedithiol (1,4-BDT) making ohmic contacts with gold in three distinct configurations of the gold electrodes. Simulations of non-equilibrium charge transport within density functional theory, despite the time-frozen ansatz and the neglection of e-ph scattering, indicate that the transmission coefficient depends upon the spin state of the itinerant electron if the electrode is an atomic wire. The projected density of states at the Au-S interface for each Au-BDT junction determined that significant anisotropy of the spin-orbital occupations at the Fermi level occurs only for the atomic wire. Current-voltage results indicate that the spin filtration ratio I_down/I_up manifests on the order of 10³ in the molecular break junction upon reaching the atomic wire limit. If the electrode is reverted to a nanowire, still with only one gold atom contacting sulfur, the difference (T_down-T_up) (E_fermi) has already diminished to zero. We reason that the reduced bond coordination of the interface gold atom with respect to the bulk electrode prompted a change in its covalent binding to sulfur, disrupting the magnetic neutrality of primarily the sulfur 3p_z, but also the gold 6s and 5d_z² valence orbitals at the Au-S quantum point interface.

Researchers should cite this work as follows:

• Avinash Prakash (2020), "Transition to Atomic Wire Electrode Actuates Gold-thiol Spin Valve," https://nanohub.org/resources/33874.

  BibTex | EndNote

1. 1st principles
2. density functional theory (DFT)
3. NEGF
4. SIESTA
5. Spin polarized transport
6. spin valve