Thickness-induced metal to insulator transition in Ru nanosheets probed by photoemission spectroscopy: Effects of disorder and Coulomb interaction.

ABSTRACT: We investigated the electronic structures of mono- and few-layered Ru nanosheets (N layers (L) with N?=?1, ~6, and ~9) on Si substrate by ultra-violet and x-ray photoemission spectroscopies. The spectral density of states (DOS) near E_F of ~6 L and 1 L is suppressed as it approaches E_F in contrast to that of ~9 L, which is consistent with the Ru 3 d core-level shift indicating the reduction of the metallic conductivity. A power law g(?)???|??-??_F|^? well reproduces the observed spectral DOS of ~6 L and 1 L. The evolution of the power factor ? suggests that the transition from the metallic state of ~9 L to the 2-dimensional insulating state with the soft Coulomb gap of 1 L through the disordered 3-dimensional metallic state of ~6 L.

SUBMITTER: Ootsuki D 

PROVIDER: S-EPMC6992751 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature