The Spin-polarized Electron Transport Properties Of The Oxygen And Hydrogen-incorporated Metal Single-atom Chains

The formation process of metallic monatomic chains and their mechanical and conduction properties have been widely investigated in the last decade, both from the experimental and the theoretical point of view. Monatomic chains have been observed for the first time in gold nanocontacts. At the same time, monatomic gold chains can be produced in mechanically controllable break-junctions, whose conductance is very close to 1 Go.Subsequently, it was discovered that monatomic chains can only be pulled for Au, Pt and Ir. Au, Ag, Cu, Fe, Pt and Ir can adsorb light impurities from outside such as H,O and CO through experimental study and theoretical calculation. Surrounding these doping of metal atom chains, people has carried out a series of experiments and theoretical calculation work. At the same time, these single atomic chains show some special conductance value, such as 1G0、0.5G0, which will not appear for single atomic chains in the vacuum environment.This paper adopts the first principle calculation combined with non-equilibrium green’s function method to study the spin-polarized electron transport properties in oxygen, hydrogen incorporated metal single-atom chain, giving a possible mechanism of specific conductance and can reasonably explain the experimental results.We first investigated the mechanism responsible for the low conductance of the Au and Cu single-atom chains. The low conductance plateau around 0.6G0 can be attributed to a distorted chain doped with an oxygen atom, while the 0.1 Go conductance comes from a linear chain incorporated with an oxygen molecule and is caused by an antibonding state formed by oxygen’s occupied frontier orbital with dz orbitals of adjacent Au atoms. For the Cu single-atom chains, the conductance about 0.3G0 is ascribed to a special configuration that contains Cu and O atoms in an alternating sequence. This exhibits an even-odd conductance oscillation with amplitude of ～0.1G0.Finally, we studied the small conductance of the oxygen, hydrogen-incorporated magnetic Fe monatomic chain. For the alternating Fe-O single-atom chain, the conductance overall decreases with an increase in O atoms and approaches nearly zero gradually which doesn’t exhibit an even-odd conductance oscillation. Fe-O single atom chain tends to be semiconductors when more than four O atoms are inserted. Both the Cu-O and the Fe-O single atom chains are half metallic when they are short. Moreover, the Fe-O single atom chain is able to filter completely either the spin-up or spin-down current depending on the polarity of the gate voltage, which suggests a perfect two-state spin filter at the single-atom level. In addition, when two hydrogen atoms are incorporated in the Fe single-atom chain, conductance of 1G0 will appear.This paper studied the mechanism of 1G0 and smaller conductance of the Au, Cu, Fe monatomic chains in the hydrogen and oxygen environment and predicted the structure of Fe-O monatomic chain which shows the spin filtering properties. Our results presented reasonable explanations for the related experimental results and predicted the structure of Fe-O monatomic chain which shows a particular spin transport properties, which give an insight on the design of atomic scale spintronic...