Observation of spin-charge separation and localization in one-dimensional quantum wires

Amir Yacoby

Andrew Meyertholen, Lingfeng M. Zhang, M. M. Fogler

Ophir M. Auslaender, Hadar Steinberg, Amir Yacoby +5 more

We report on measurements of quantum many-body modes in ballistic wires and their dependence on Coulomb interactions, obtained by tunneling between two parallel wires in an GaAs/AlGaAs heterostructure while varying electron density. We observed two spin modes and one charge mode of the coupled wires and mapped the dispersion velocities of the modes down to a critical density, at which spontaneous localization was observed. Theoretical calculations of the charge velocity agree well with the data, although they also predict an additional charge mode that was not observed. The measured spin velocity was smaller than theoretically predicted.

Peter M. Andersen, S. H. Sundberg, O. Sveen +1 more

Amir Yacoby, Ophir M. Auslaender, Hadar Steinberg +5 more

Abstract Using a double wire geometry we probe the quantum many‐body modes in ballistic wires and their dependence on Coulomb interactions. The wires are fabricated using the cleaved edge overgrowth method. We clearly observe two spin modes and one charge mode of the coupled wires. We map the dispersion velocities of the modes down to a critical density at which spontaneous localization is observed. Theoretical calculations of the charge velocity agree well with the data, although they also predict an additional charge mode that is not observed. Surprisingly, the suppression of the spin velocities does not depend on density. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Ulrich Zülicke, Michele Governale

Interactions in one-dimensional (1D) electron systems are expected to cause a dynamical separation of electronic spin and charge degrees of freedom. A promising system for experimental observation of this non-Fermi-liquid effect consists of two quantum wires coupled via tunneling through an extended uniform barrier. Here we consider the minimal model of an interacting 1D electron system exhibiting spin-charge separation, and calculate the differential tunneling conductance as well as the density-density response function. Both quantities exhibit distinct strong features arising from spin-charge separation. Our analysis of these features within the minimal model neglects interactions between electrons of opposite chirality, and therefore applies directly to chiral 1D electron systems realized, e.g., at the edge of integer quantum Hall systems. Physical insight gained from our results is useful for interpreting current experiment in quantum wires, as our main conclusions still apply with nonchiral interactions present. In particular, we discuss the effect of charging due to applied voltages, and the possibility to observe spin-charge separation in a time-resolved experiment.