title: A reversible strain-induced electrical conductivity in cup-stacked carbon nanotubes.
abstract: We have used in situ current-voltage measurements of cup-stacked carbon nanotubes (CSCNTs) to establish reversible strain induced (compressive bending) semiconducting to metallic behavior. The corresponding electrical resistance decreases by two orders of magnitude during the process, and reaches values comparable to those of highly crystalline multi-walled carbon nanotubes (MWCNTs) and graphite. Joule heating experiments on the same CSCNTs showed that the edges of individual cups merge to form "loops" induced by the heating process. The resistance of these looped CSCNTs was close to that of highly deformed CSCNTs (and crystalline MWCNTs), thus suggesting that a similar conduction mechanism took place in both cases. Using a combination of molecular dynamics and first-principles calculations based on density functional theory, we conclude that an edge-to-edge interlayer transport mechanism results in conduction channels at the compressed side of the CSCNTs due to electronic density overlap between individual cups, thus making CSCNTs more conducting. This strain-induced CSCNT semiconductor to metal transition could potentially be applied to enable functional composite materials (e.g. mechanical sensors) with enhanced and tunable conducting properties upon compression.
authors.affiliation: Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Thomas C
authors.initials: TC
authors.lastname: O'Connor
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Higashiyama
authors.forename: Kohei
authors.initials: K
authors.lastname: Nishi
authors.forename: Kazunori
authors.initials: K
authors.lastname: Fujisawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Muramatsu
authors.forename: Yoong Ahm
authors.initials: YA
authors.lastname: Kim
authors.forename: Bobby G
authors.initials: BG
authors.lastname: Sumpter
authors.forename: Vincent
authors.initials: V
authors.lastname: Meunier
authors.forename: Mauricio
authors.initials: M
authors.lastname: Terrones
authors.forename: Morinobu
authors.initials: M
authors.lastname: Endo