Coulomb interactions have been predicted to have a profound effect on the behaviour of electrons in one dimension as predicted for a spin-charge separation of a Tomonaga-Luttinger Liquid (TLL), the simplest analytic model of an interacting 1D system. Verification of a TLL is an important goal in experimental solid-state physics, with relevance to quantum devices and the theory of high-Tc superconductors. Determining the extent of its applicability would also provide a major test of more general methods of modelling interaction effects. In this talk, I will present the experimental results from momentum-conserved tunnelling between an array of GaAs quantum wires (1D) and adjacent two-dimensional electron gas (2D), in which we observed spin-charge separation and a power-law suppression of tunnelling into the wires [1]. The use of an array of wires averages out impurity effects and allows the lowest 1D subband to be probed with precise control of electron density [2]. We observed spin-charge separation in the dispersion relation of the 1D wires by measuring tunnelling conductance whilst varying the in-plane magnetic field and the dc-bias simultaneously. We find that the separation persists beyond the regime where the TLL approximation should hold. Furthermore, the measured 1D-2D tunnelling current is suppressed at zero dc-bias in the presence of a magnetic field, confirming that interactions are important in these quantum wires. This suppression has been measured as a function of temperature and source-drain voltage and both have similar power-law dependences. We compare the interaction parameters deduced from each of these measurements. [1] Y. Jompol, C. F. B. Ford, J. P. Griffiths, I. Farer, D. Anderson, D. A. Ritchie, T.W. Silk, and A.J. Schofield, Spin-charge separation in a Tomonaga-Luttinger liquid probed by tunnelling into a two-dimensional electron gas (under peer review for a publication in Science). [2] Y. Jompol, C. F. B. Ford, I. Farer, D. Anderson, D. A. Ritchie, T. W. Silk, and A.J. Schofield, Probing e–e interactions in a periodic array of GaAs quantum wires, Physica E 40, 1220 (2008).
Nanoscience Technology Center and Department of Physics, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, FL 32826 USA.