Electronic and thermal spin effect of molecular nanowires between graphene electrodes

Based on the first-principles method, the electronic spin transport properties of terphenyl molecule bridging in zigzag graphene nanoribbon (ZGNR) electrodes with three connecting linkages were investigated, including dangling, heptagon, and pentagon-linkages. For the pentagon-linkage system, we observed a perfect spin filtering effect in the parallel (P) configuration (at almost 100% spin polarization), with the heptagon-linkages system following next (85-95% spin polarization), however, the spin filtering effect is almost negligible for the dangling-linkages system. In the antiparallel (AP) configuration, the pentagon- and heptagon-linkage systems also showed a high spin filtering effect. The terphenyl molecule was then replaced by carbon chains based on the pentagon-linkages, and these devices also show a perfect spin filtering effect (100% spin polarization). Finally, the thermally induced spin transport for the carbon chains model with pentagon-linkages was explored, and this system exhibits almost 100% thermal spin polarization.