title: Electrically induced ambipolar spin vanishments in carbon nanotubes.
abstract: Carbon nanotubes (CNTs) exhibit various excellent properties, such as ballistic transport. However, their electrically induced charge carriers and the relation between their spin states and the ballistic transport have not yet been microscopically investigated because of experimental difficulties. Here we show an electron spin resonance (ESR) study of semiconducting single-walled CNT thin films to investigate their spin states and electrically induced charge carriers using transistor structures under device operation. The field-induced ESR technique is suitable for microscopic investigation because it can directly observe spins in the CNTs. We observed a clear correlation between the ESR decrease and the current increase under high charge density conditions, which directly demonstrated electrically induced ambipolar spin vanishments in the CNTs. The result provides a first clear evidence of antimagnetic interactions between spins of electrically induced charge carriers and vacancies in the CNTs. The ambipolar spin vanishments would contribute the improvement of transport properties of CNTs because of greatly reduced carrier scatterings.
authors.affiliation: Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Matsumoto
authors.affiliation: Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yanagi
authors.affiliation: Department of Applied Physics, Waseda University, Tokyo 169-8555, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Takenobu
authors.affiliation: Division of Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Okada
authors.affiliation: 1] Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan [2] Japan Science and Technology Agency (JST), PRESTO, Kawaguchi, Saitama 322-0012, Japan [3] Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Marumoto