Condensed Matter Physics Seminar
2 p.m., Thursday, March 4, 2004
Room 1201, Physics Building
Spin–Charge Separation and Localization in One Dimension Measured Using
Momentum Resolved Tunneling
Amir Yacoby
(Weizmann Institute, on sabbatical at Harvard University)
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 electron 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 loses translation
invariance and becomes localized. We find that the localization length
corresponds to the inter-electron spacing determined by the 1D electron density.
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Host: Yakovenko
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