Condensed Matter Seminar Series

Observation of Spin-Charge Separation and Spontaneous Localization in 1D

Amir Yacoby

Weizmann Institute & Harvard University

Thursday December 11, 1:30 pm, Room 234, Physics Building

Abstract: We have measured the collective excitation spectrum of interacting electrons in one-dimension. The experiment consists of controlling the energy and momentum of electrons tunneling between two clean and closely situated, parallel quantum wires in a GaAs/AlGaAs heterostructure while measuring the resulting conductance. At high elelctron densities the measured excitation spectrum clearly deviates from the non-interacting spectrum, attesting to the importance of Coulomb interactions. Notable is the observation of two excitation branches indicating spin - charge separation. In short wires, 6 microns and 2 microns long, finite size effects, resulting from breaking of translational invariance, are observed. Here spin – charge separation is manifested through Moiré patterns generated from the spin and charge excitation branches. At low electron densities the system abruptly looses translation invariance and becomes localized. We find that the localization length corresponds to the inter-electron spacing determined by the 1D electron density.