Large oscillating nonlocal voltage in multiterminal single-wall carbon nanotube devices

Abstract

We report on the observation of a nonlocal voltage in a ballistic (quasi)-one-dimensional conductor, realized by a single-wall carbon nanotube with four contacts. The contacts divide the tube into three quantum dots, which we control by the back-gate voltage ${V}_{g}$. We measure a large oscillating nonlocal voltage ${V}_{\mathrm{nl}}$ as a function of ${V}_{g}$. Though a resistor model that includes the impedance of the voltmeter can account for a nonlocal voltage including change of sign, it fails to describe the magnitude properly. The large amplitude of ${V}_{\mathrm{nl}}$ is due to quantum interference effects and can be understood within the scattering approach of electron transport.