title: Thermopower of benzenedithiol and C60 molecular junctions with Ni and Au electrodes.
abstract: We have performed thermoelectric measurements of benzenedithiol (BDT) and C60 molecules with Ni and Au electrodes using a home-built scanning tunneling microscope. The thermopower of C60 was negative for both Ni and Au electrodes, indicating the transport of carriers through the lowest unoccupied molecular orbital in both cases, as was expected from the work functions. On the other hand, the Ni-BDT-Ni junctions exhibited a negative thermopower, whereas the Au-BDT-Au junctions exhibited a positive thermopower. First-principle calculations revealed that the negative thermopower of Ni-BDT-Ni junctions is due to the spin-split hybridized states generated by the highest occupied molecular orbital of BDT coupled with s- and d-states of the Ni electrode.
authors.affiliation: Graduate School of Engineering Science, Osaka University , 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan.
authors.forename: See Kei
authors.initials: SK
authors.lastname: Lee
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Ohto
authors.forename: Ryo
authors.initials: R
authors.lastname: Yamada
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tada
keywords: Thermoelectricity; density functional calculation; molecular junctions; spin-splitting; thermopower